The last-ever penny will be minted today in Philadelphia

We eliminated pennies in Canada in 2012 and the transition was a non-issue. The vast majority of retailers would round cash transactions to the nearest $0.05, but a few would round down to the nearest $0.05 in favor of the customer. https://en.wikipedia.org/wiki/Withdrawal_of_low-denomination...

Canadian cash is better than American cash in several ways: No penny, durable polymer banknotes (instead of dirty wrinkly cotton paper), colorful banknotes (instead of all green) that are easy to distinguish, $1 and $2 coins in wide circulation (instead of worn-out $1 bills).

The linked article raises a few problems that the US could have with that solution:

> Four states - Delaware, Connecticut, Michigan and Oregon - as well as numerous cities, including New York, Philadelphia, Miami and Washington, DC, require merchants to provide exact change.

This seems like a non-issue as long as they round the price down. Because there's no law that the store can't discount their total by a small amount and then provide exact change.

"Congratulations customer, we have a special coupon today for $0.03 off your purchase. Here's your change :)"

I don't see why you couldn't do it in either case. If you modify the actual price, then you are giving exact change. Why wouldn't round() be as valid a price modification as floor()?