Having worked in a toll booth through grad school, I have a problem with the way people hand others money that contains both bills and coins. I've seen several different methods:
1. There's the place the coins on the president's face of the bill and then fold the bill over the coins into a little package. Just asking for disaster and then the bill is wrinkled and has to be unfolded.
2. There's the hold the bill on top of the coins and then during the hand off try to slip the coins into the receiver's hands. It is impossible to see the coins and is just asking for them to fall on the ground.
3. There's the hold the bills in your palm and holding the coins with the forefinger and thumb. This usually results in shoving the bills into someone's hand and forcing the coins into the receiver's hand. This results in the receiver having to delicately pull the bill out from under the coins in his hand to count the money.
4. There's the wad everything into a ball in your hand and holding a fist out in front of you. How is anyone supposed to grab something that you are letting go of from fist. Just plain stupid.
5. My preferred method is to give the coins and then the bills in two separate movements. This allows the person receiving the money to count the coins and then accept the bills. The order is important...giving the bills and then the coins often results in having to say "I've got the 11 cents.".