When you say 'small shops', I wouldn't try to crack a $100 bill when I was going to buy something for $10. My personal rule of thumb is that I wouldn't use a $100 bill at a smaller place unless I was spending at least $50, but that is more out of respect for a merchant. It's very hard for a small merchant to make change if his cash register is full with $100 bills. We usually break our $100 bills at a grocery store or when buying a meal.