Making Change In New York

Since I came to Manhattan, I've noticed a weird phenomenon relating to how people make change when I'm at a checkout counter. Where I come from, if the person at a deli counter rings you up for $10.35 in groceries, and you give him a $20 bill, a quarter and a dime, you should get a $10 bill back. Like everybody else, I dig in my pockets for change so that I won't have to carry around a bunch of jingling coins all the time.

Contrast that with the usual practice in Manhattan. In the above scenario, I'd get back two $5 bills, or a $5 and five $1 bills. This has happened consistently since I've lived here, and I've always wondered why.

Last week, I paid for $7.46 of groceries with a $20 bill and got back $12 in singles, five dimes and four pennies. The checkout guy had $10 and $5 bills in the cash register, as well as quarters and nickels, but gave me this weird arrangement anyway.

Anyone else noticing this weirdness? I've always wondered why it happens, but haven't been able to figure it out.