Surely your inventory/POS systems need to know what price/tax rates to charge anyway. I understand your point in the context of an ad in a magazine offering a g

Surely your inventory/POS systems need to know what price/tax rates to charge anyway. I understand your point in the context of an ad in a magazine offering a good at a particular price, but I don't think it makes sense at all in the context of a store with tickets on items that don't actually correspond to the price at the till.