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).

There are several US states where, by law, retailers are not allowed to give preferential treatment to credit card paying customers over cash paying ones. Which means, in those states, retailers will be required to always round transactions to the cash paying customer's benefit, where in other states the retailer is allowed to round to the nearest 5 cents. This is going to cost large retailers millions.

Interestingly many of them had already put the work into updating the cash register software to allow for this due to the penny shortages during covid.

It doesn't cost anyone anything. They can just raise prices 3 cents or whatever.