A noticeable number of places around me in an urban area in the USA already now have signs up saying they won't make any coin change at all! Pay with a card, or exact change, or they'll round up to the dollar keep the difference.

Sometimes the sign says "due to the penny shortage" and has been up for a year or whatever, I dunno. But they aren't just not giving you pennies in your change, they are refusing any coins in your change. I am curious as to the motivation, I could guess but it's not obvious to me. They will still take coins as payment, just not give them as change.

You can either put payments into the register or the safe.

If it goes into the safe, it's nearly impossible to steal because there's a time lock preventing the cashier from accessing it. But you can't make change.

This means you have a optimization problem to have the minimum possible cash in the register to meet all change needs.

Eliminating denominations makes the optimization problem easier, if nothing else.