How to produce formatted output in Powershell?

That's not how we do things in PowerShell. Your code is repetitive, hard to read and hard to maintain.

I'd start with something like this:

$Products = @'
Product,Price,TaxRate,Quantity
Bread,1.75,0,
Milk,3.29,0,
Chips,4.19,0,
Potatoes,1.49,0,
Batteries,2.39,8.25,
Vitamin,4.89,8.25,
'@ |
    ConvertFrom-Csv

$ShoppingCart = 
foreach ($item in $Products) {
    [int]$Item.Quantity = Read-Host ('How many items of {0,9} (${1} each)' -f $Item.Product, $item.Price)
    $item
}

$Checkout =
    $ShoppingCart |
        Select-Object -Property Product,Price,Quantity,
            @{Name = 'SubTotal'; Expression = {[Math]::Round($([Float]$_.Price * [Int]$_.Quantity * (1 + ($([Float]$_.TaxRate) / 100))),2)}}

$Total = ($Checkout | Measure-Object -Property Subtotal -Sum ).Sum

$Checkout 
"`nTotal:  {0}" -f $Total

The output would look something like this:

Product   Price Quantity SubTotal
-------   ----- -------- --------
Bread     1.75         5     8,75
Milk      3.29         4    13,16
Chips     4.19         3    12,57
Potatoes  1.49         6     8,94
Batteries 2.39         2     5,17
Vitamin   4.89         8    42,35

Total:  90,94

Of course there's room for improvement. ;-)

BTW: The output shows a comma as the decimal point because my language setting is not english! ;-)

Working now, I needed to remove "" from variables so Powershell can interpret them as floats instead of a string.

#file: daily_needs_store.ps1
#
Write-Host ("`n{0,29}" -f "Affordable Daily Needs")
Write-Host "This Program will prompt for 10 items."
Write-Host "Enter quantity of each item purchased."

$TaxRate = 8.25

[float]$breadCount = Read-Host ("{0,-45}" -f "How many loaves of Bread (`$1.75 each)")
[float]$milkCount = Read-Host ("{0,-45}" -f "How many Gallons of Milk (`$3.29 each)")
[float]$chipsCount = Read-Host ("{0,-45}" -f "How many Bags of Chips (`$4.19 each)")
[float]$potatoesCount = Read-Host ("{0,-45}" -f "How many Pounds of Potatoes (`$1.49 each)")
[float]$bananasCount = Read-Host ("{0,-45}" -f "How many Pounds of Bananas (`$0.49 each)")
[float]$beefCount = Read-Host ("{0,-45}" -f "How many Pounds of Beef (`$5.29 each)   ")
[float]$tomatoesCount = Read-Host ("{0,-45}" -f "How many Pounds of Tomatoes (`$0.99 each)")
[float]$applesCount = Read-Host ("{0,-45}" -f "How many Pounds of Apples (`$1.29 each)")
[float]$batteriesCount = Read-Host ("{0,-45}" -f "How many 2-packs of AA Batteries (`$2.39 each)")
[float]$vitaminCount = Read-Host ("{0,-45}" -f "How many Bottles of Vitamin (`$4.89 each)")

Write-Host ("{0,-50}" -f "===================================")
Write-Host ("{0,29}" -f "Affordable Daily Needs")
Write-Host ("{0,28}" -f "4715 San Pedro Avenue")
Write-Host ("{0,29}" -f "San Antonio, TX 78217")
Write-Host ("{0,27}" -f "Phone: 210-128-1919")
Write-Host ("{0,-50}" -f "-----------------------------------")

[float]$total = 0.0;
[float]$totalTax = 0.0;
[float]$subTotal = 0.0;

$breadCost = $breadCount * 1.75
$subTotal = $subTotal + $breadCost

$milkCost = $milkCount * 3.29
$subTotal = $subTotal + $milkCost

$chipsCost = $chipsCount * 4.19
$subTotal = $subTotal + $chipsCost

$potatoesCost = $potatoesCount * 1.49
$subTotal = $subTotal + $potatoesCost

$bananasCost = $bananasCount * 0.49
$subTotal = $subTotal + $bananasCost

$beefCost = $beefCount * 5.29
$subTotal = $subTotal + $beefCost

$tomatoesCost = $tomatoesCount * 0.99
$subTotal = $subTotal + $tomatoesCost

$applesCost = $applesCount * 1.29
$subTotal = $subTotal + $applesCost

$batteriesCost = $batteriesCount * 2.39
$subTotal = $subTotal + $batteriesCost
$totalTax = $totalTax + ($batteriesCost * (1 + ($TaxRate/100)) - $batteriesCost)

$vitaminCost = $vitaminCount * 4.89 
$subTotal = $subTotal + $vitaminCost
$totalTax = $totalTax + ($vitaminCost * (1 + ($TaxRate/100)) - $vitaminCost)

$total = $subTotal + $totalTax


Write-Host ("{0,-10} {1,4} {2,11} {3,6}" -f "Item", "Qty", "Price/Unit", "Cost" )
Write-Host ("{0,-50}" -f  "-----------------------------------")
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Bread", $breadCount, "`$1.75", $breadCost )
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Milk", $milkCount, "`$3.29", $milkCost )
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Chips", $chipsCount, "`$4.19", $chipsCost )
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Potatoes", $potatoesCount, "`$1.49", $potatoesCost )
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Beef", $beefCount, "`$5.29", $beefCost )
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Tomatoes", $tomatoesCount, "`$0.99", $tomatoesCost )
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Apples", $applesCount, "`$1.29", $applesCost )
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Batteries", $batteriesCount, "`$2.39", $batteriesCost )
Write-Host ("{0,-10} {1,4:N1} {2,9} {3,8:N2}" -f "Vitamins", $vitaminCount, "`$4.89", $vitaminCost )
Write-Host ("{0,-50}" -f "-----------------------------------")
Write-Host ("{0,-10} {1,23:c2}" -f "Subtotal", $subTotal) 
Write-Host ("{0,-10} {1,22:c2}" -f "Tax `@ 8.25`%", $totalTax) 
Write-Host ("{0,-50}" -f "-----------------------------------")
Write-Host ("{0,-10} {1,23:c2}" -f "Total", $total) 
Write-Host ("{0,-50}" -f"===================================")
Write-Host "Sales Clerk: John Doe"
Write-Host "Counter#: 7"
Write-Host "Date:"(Get-Date)

1. Reduce dashed lines to just 35 characters.
2. REMOVE double quotes from all variables, the format operator -f thinks they are strings, but we want it to know that they are actually numbers.
3. Do NOT place a dollar sign in front of total. Use the correct formatting strings.
4. Use one type of formatting string on Qty column, but a different type for Cost column.
5. Use negative alignment on first row, positive alignment for numbers/money.
6. Reduce the size of most alignment numbers, that thing way too wide!
7. You need 3 rows at the bottom, not 2. One for Subtotal, then Tax, and finally Total.
8. Go to bed at decent hour, same time each night, and get at least 7.5 hours of sleep per night.