Several reasons, it really is a mess.

The local tax is set by multiple independent tax authorities that change their taxes independently, the tax you see is the aggregate of those independent authorities computed separately, which do not coordinate with each other.

Some of these taxes are conditional at point-of-sale, late-binding the taxes, such that different customers are subject to different rates across these tax authorities such that it is unlikely to round to exactly 5c.

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.

And on top of all of this, the Federal government does not have the authority to regulate the way States and various locales structure their sales taxes. It is a herding cats problem.

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metabagel 11 hours ago | parent | next [-]

> 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.

	▲	jandrewrogers 11 hours ago \| parent [-]
		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.

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pests 11 hours ago | parent | prev [-]

I've seen stores advertise "we pay your sales tax" like furniture outlets. Wouldn't this allow for legal priced items?