> It is widely illegal to not display the true price and taxes paid separately. Trying to retcon a price and taxes for rounding purposes that is also strictly consistent across customers so as to not violate the law is not trivial.

Having lived in Europe, this should be changed. It makes it infeasible to keep track of your total bill as you shop. The amount without tax should be printed on the receipt, if you care to reference it.

The issue is that the legal change would have to be made independently across thousands of decentralized tax authorities. Herding that many cats is infeasible so it can't be part of a plausible solution. In some jurisdictions, the legal process required to make the changes have effectively insurmountable voting thresholds.

It may not be convenient but any realistic solution has to recognize the hard facts that shape the nature of problem.