In Canada, with sales taxes varing from 5% to 15% by province, we round to the nearest nickel on cash transactions. Non-cash transactions are rounded to the nearest penny as usual. Works fine IMO.
Note that the rounding is to the nearest nickel, neither up nor down. So it favours neither buyer nor seller; it all nets out about the same for all in the end.
We stopped minting pennies 10 years ago. They're still legal tender but rare to see since there's no need with 5-cent cash rounding conventions now. There were brief popular grumblings and misplaced arithmetic anxiety leading up to the death of the penny. I expect the same when we bury the nickel and I bet few will miss it either when its time comes. And then the dime.
Of course one can construct amusing temporary edge cases or arbitrage opportunities when buying specific quantities of specifically priced items in the presence of any new rounding rules. The market will respond.
I can't find a proper citation, but rounding is undefined.
The recommended guideline[0] is to round to the nearest 5¢.
This article from 2013 is my closest citation to "undefined behaviour"[1]
> These guidelines are only a suggestion though and there is currently no law that specifies how retailers must round.
I don't know since ~2013 if anything has been decided to make those guidelines "law". I couldn't find anything quickly in the SEO cesspool that is modern web search.
In practice, as an American, we have a custom of paying merchants to cheat us out of a penny. As in, if a charge come out to $4.99, we hand the cashier a $5 bill and a penny, with the expectation of not receiving change. We also have leave-a-penny-take-a-penny trays by some cash registers with free pennys funded by customer donations.
Note that the rounding is to the nearest nickel, neither up nor down. So it favours neither buyer nor seller; it all nets out about the same for all in the end.
We stopped minting pennies 10 years ago. They're still legal tender but rare to see since there's no need with 5-cent cash rounding conventions now. There were brief popular grumblings and misplaced arithmetic anxiety leading up to the death of the penny. I expect the same when we bury the nickel and I bet few will miss it either when its time comes. And then the dime.
Of course one can construct amusing temporary edge cases or arbitrage opportunities when buying specific quantities of specifically priced items in the presence of any new rounding rules. The market will respond.