Okay kiddo, imagine you go to the store and buy something. When you check out, the cashier tells you that you have to pay a little extra money, and that extra money is called "sales tax". This sales tax is added to the price of the thing you bought, and that's how the government gets some money to help with things like building roads or schools.
But a long time ago, people didn't use money bills and coins like we do now. They used little metal tokens that were worth a certain amount of money. And when you bought something, you would give the cashier a certain number of tokens to make up the total price.
Now, what's special about these tokens is that they were made just for paying sales tax. So if you bought something that cost 30 cents and the sales tax was 3 cents, you could give the cashier a 30-cent token and a 1-cent token, and they would give you back a 2-cent token as change.
Sales tax tokens were used a lot during the Great Depression, when money was really scarce and people wanted to save every penny they could. In fact, some states even made it a law that stores had to give out sales tax tokens instead of money for change!
Nowadays, we don't use sales tax tokens anymore since we have money bills and coins that can easily add up to the correct amount with sales tax. But it's still kind of cool to think about how people used to pay for things differently, isn't it?