You can prepare the exact amount in cash while you're in line. Then it's 0.
Many (all?) European countries include VAT in the price, but prices of 9.99, 0.99 etc. are all too common.
(VAT is a bit different from the way the US-style sales tax for other reasons: https://en.m.wikipedia.org/wiki/Value-added_tax )
It's difficult, but everyone in a local area knows already.