When I write a check I always put it into the register. Good thing to do, but here's a way to pocket some extra change while doing so.
When I put in a transaction, say Gas $13.85, I'll add it in my register as $14.00 even. So in my running totals it is much easier to do running math, and some small change is always left behind as a buffer.
Sure .15 cents isn't much but it adds up. Over a year I had almost $65.00 worth of 'Spare Change' that I just bumped into my savings account.