Here's an activity to do with your kids: run around this house and find loose change. Kids from an incredibly young age can sort money. Being able to sort money is the first crucial step in learning how to identify coins and their value.
It is also a very handy skill for older kids to be able to sort, count and fill their own coin wrappers. Why pay a percentage of money at the market to have a machine sort it for you when you have perfectly capable kids at home to do it? You could even offer a percentage to your kids to sort, count and fill for you, if you really want to pay someone to do it.
At our house we have a family jar that loose money goes into. Every once in a while we sort it, count it and fill the wrappers to take to the bank. We use the money to go toward a group gift for our family. . An important lesson here is that kids can see that it all adds up. A little bit here, a little bit there, and pretty soon we have enough for a new game!