Penalty box and crabby carpet!
My kids were, and still could be, put into the penalty box.
The penalty box is a taped square on the floor in the living room corner. When a bad behavior occurred, we gave a brief, stern explanation and sat them in the penalty box for as many minutes as old. Many times they would go again and again until the naughty behavior stopped (hitting, biting, throwing objects, hair pulling, sassy, etc.).
The crabby carpet was in the laundry room. It was a boring, yet safe area in our home. If they were throwing a tantrum or their mood was out of control crying, they sat on the crabby carpet until they were "happy." We would say just that..."You will sit on the crabby carpet until you are happy." Then we didn't have to see or hear it, much anyhow. Plus they didn't get the attn from the behavior. They could leave the crabby carpet when they came to say "I am sorry and happy now." The really neat thing about the crabby carpet is that it can go with you ANYWHERE (grandma's, vacation, store)! During those trying years, I made sure my sons knew I was packing it in the car. "I can get the crabby carpet out and you can sit on it right here in the store."

I never had to in the store, but I did once at the baseball fields.
Good luck!