I usually have two carts at the grocery store. One for groceries and one for various children. I can't go to the grocery store without at least 3 people stopping me to ask “Are they all yours!?” but that's a topic for another list.
Anyway, if you can't get to the grocery store sans children, then you have to make sure that you lay down the law before walking in. Rule number one: “NO 'Gimmees.'“ Let them know that there will be consequences, and then keep your word!
Without this discipline, I am likely to give in if it has been a long tired day and I just can't stand to listen to a child endlessly whine about how deprived and abused he is because I won't buy a $4.69 box of Pokemon cereal. Nip it in the bud!!!
My grocery store has mechanical pony rides for just a penny. If a child dares to say anytime during our grocery trip, “I want,” “Can I have,” or “Gimmee!” they do not get to ride the pony at the end. I had to endure a little temper tantrum the first time or two, but you can bet the farm that they quickly learned not to bug me for goodies.
Another tactic is to grab a special treat at the beginning of the trip - perhaps a cookie or string cheese. As soon as the “gimmee” leaves their lips, the treat is promptly put back. And don't give them a second chance - the very first infraction gets a negative result. Better they cry now than
The “gimmees” isn't an issue with my older children, as they have been trained from when they were very little. (Though they have been known to say things like “Hey Mom we ought to get that when it goes on clearance!” Which I don’t mind at all.) If the “gimmees” are a problem with your older kids, you'll need a different punishment than skipping a pony ride or a cookie, of course. Perhaps older children with the “gimmees” can be given the task of unloading and putting away the groceries all by themselves, right after they draw a nice warm bubble bath for you to relax in (Calgon take me away!).
I promise that the grocery shopping tips are going to get meatier in the weeks ahead but, as I said before, we are taking baby steps. Make sure this week that you are implementing both Tip 1 and Tip 2.