Earlier quoted context omitted.
Additionally, sales tax is sometimes not required, either because the product or the reason for purchase is exempt. Computers can deal with the latter, signage can't.
For bricks and mortar stores, if the majority of people due to pay the tax are capable of rounding up a posted price of $fee + tax, the minority eligible for tax exemptions are capable of rounding down a posted price of $fee - tax Might be a little different for online stores where tax can't be calculated until they know which of the many different local tax codes the sale is being made under, but as you've already n…
Except for businesses, there isn't the situation as in the US, where the retailer is responsible for verifying that a customer is tax-exempt. People on the equivalents of food stamps pay the VAT; yes the money just goes in a circle back to the government, but it's probably easier accounting for everyone.