Taxes in Argentina are variable, so we let you set them up in two different ways. Both are correct.
Option A: everything in the percentage
You enter VAT + gross receipts tax (Ingresos Brutos) together in Store taxes, and it's deducted order by order. It's the simplest option.
Option B: separately
In Store taxes you enter only the gross receipts tax percentage, which is what's actually withheld from each sale. Then, at the end of the month, you add the VAT you actually paid as an additional fixed cost.
Option B usually makes sense when your input/output VAT isn't stable: an average percentage would distort your numbers month to month, and this way you enter the real amount once you know it.
Keep in mind that by including VAT in your product cost you're already accounting for the VAT on purchases. The store tax percentage models what you actually have left to pay.