Paul,
I turn the daughter loose on my change jar about twice a year. Before she starts rolling, she has to tell me which coins (pennies, nickels, dimes, guarters, halves, or dollars she wants. She rolls all the coins except the ones that don't fill a roll, then we take them to the bank and deposit them.
At first she always picked quarters because it seems that they add up quicker. Funny though, every time I have more dimes than anything else. Jessa has started choosing them, now.
Sure it costs me more than 8%, but the anticipation for "rolling day" and the fun we have kidding each other while she works makes it all worth it to this old man.
Let's face it, there aren't that many times a sixteen year old wants to hang out with Dad rather than being with buddies.
grizzly bare