When my kids are disobeying while we are running errands, the consequence is “hand on the cart.” They are kept close to the cart the entire time with one hand grasped onto the side. If they have been doing that really well, I might give them one more chance. It is a way to quickly get their hands from touching and grabbing items and keeps them right where you want them. My kids have become pretty easy to have on errands because of this technique.
we call this the “touch” rule… if my son acts up at the store i tell him “touch” and he has to remain touching the cart or me until he gets his second chance! and EVERYTIME we are in a parking lot i tell him touch and he remains touching either the vehicle or the cart until it is safe to get into the car.