Grocery stores still accept $100s. It is the places where the average purchase is much smaller (or robberies are more common), like coffee shops or convenience stores. Gas stations might accept the bill but only if the change needed is under $20. And then they drop the bill in the safe, rather than put it in the till.

Grocery stores used to be the king of cash.

It was not uncommon for someone to show up with their paycheck to do their weekly shopping, handing it over to the cashier and taking the rest in change. The amount of cash that worked through a busy grocery store must have been pretty amazing.

Put the overage in the safe.

I’m sure the exact policy adopted, if any, depends on a number of factors such as how often cash is used and typical purchase size.