Currency
From PinataIsland.info, the Viva Piñata wiki
The currency in the game is foil-wrapped chocolate coins. You can get currency by trading in your piñata. You may also be able to get chocolate coins for selling recources that your pinatas produce, like Buzzlegum's honey. You need to pay Helpers with chocolate coins in order to keep them happy, and if they're not satisfied they'll walk off the job. They can also be used to buy new things for your garden from the shop. It should be noted that there are silver and gold coins,the gold probably being worth more.