There have been times in my life where I've scrounged for change in my car, couch & purse because I needed money to pay for diapers or other important kid items.
I would be a blend of horrified, angry & sad if I made it up to the cash register with a handful of change to pay for my items only to be told they only accept a certain amount of change as payment.
Read how this Portland, Oregon had to deal with this situation.
Sure it might be annoying for the cashier. I was a cashier just outside of Flint, Michigan briefly once upon a time and I remember counting out a lot of change from elderly couples. Hey I understood. Money is money and like the woman in that story linked above. "If the government issues you the money they "stores" should take it." As a small handmade artist even at craft shows I accept change as payment.
Hard times falls upon the best of us why not do what we can and help someone out?