J.J.
C.,
I can relate as I have a 3 yr. old myself. My son went through that for about 6 months and now he is just fine at the grocery store. I have found the following works for us... I let him choose a bag of chips (I wish I could say sack of carrots but he won't eat veggies) or something he can munch on while riding in the cart as I. I then give the empty or half eaten bag to the cashier with all my other items to pay for and he is happy because he is full. He doesn't even notice the candy anymore. We also go to the store when he wakes from his afternoon nap so this idea suffices as his afternoon snack. Plan on a later dinner. Works for me!!!! Good luck.
J.