This is a little tip that I think would help most men. If you keep a quarter in your pocket then you should never receive more than 75 cents in change. This can really cut down on jingly pockets.
I settled on a quarter because anything smaller is virtually useless, and anything larger requires two coins or rarely used coins. Fifty cent pieces are rare and annoy cashiers, but that would be the optimal coin to carry. Two coins doesn't work because they would always clank together, the exact scenario you're trying to avoid.
As a variation, you could carry two quarters in separate pockets. You could carry a penny as the second coin, to avoid getting four pennies as change. If you can and do carry a coin purse, then you're probably better off carrying some other combination, maybe 41 cents (a quarter, a dime, a nickel, and a penny) or 52 cents (two quarters, two pennies).