Don't you think using percentages in calculations is always a nasty thing? Well, the developer of finefoods-online.com definitely does.
Some translations from Dutch:
BTW: VAT (taxes...)
Hoeveelheid: Amount
Prijs/Stuk: Price/Unit
Totaal(bedrag): Total (price)
I for one think it's strange to see how subtracting and then adding the VAT can result in a different price then the original!
Link: finefoods-online.com