This is something my hubby and I have been doing for years. We pay for our purchases with paper cash and put all the days change in the change jar. Our Change jar is a rather large container that use to have pretzels in it. You will be amazed at how fast those nickles, dimes, pennies and quarters add up.
Save even more by wrapping them yourself. Don't use Coinstar or any other counting machine they can cost up to 10% of the total That's $10 for every $100. If you don't feel like wrapping them yourself then pay your kid the $10 to wrap them for you then they can save up for something they want. Don't by you coin wrappers either you can go to your bank and get FREE coin wrappers.
After you've wrapped up the coins make sure they go into savings better still deposit them into a vacation or Christmas club account where you can't touch them until it's time. Even if you don't use it for that purpose it's still a good way to keep yourself from spending it and a great way to save up a safety net for emergencies.