It takes a lot of work when it comes to planning to make sure we don't go over our grocery store budget, but we continue to set records when it comes to coming in under our food budget each month.
Set yourself a budget. You don't have to do this with your kids; they won't understand all the things you need to pay for. But when you go to the grocery store, you can certainly explain to them how much money you have allocated for this shopping trip, and have them add up the cost as you fill the basket.