One of our math objectives in first grade is to count coins. Students should recognize pennies, nickels, dimes, and quarters and know the value of each. They should also be able to determine the value of collections of pennies, nickels, and dimes (quarters don't come in until second grade).
After spending some fabulous time sorting real coins and counting them (from the Haiti Penny Drive) we used toy coins to 'purchase' items. The students did a fabulous job determining what coins to use to buy different things. They are all quite good at it. They could help you out when shopping!