That didn't work for Lestor Maddox (later governor) in Atlanta, Georgia, years ago at his chicken resturant, because the feds found out-of-state license plates on cars in the parking lot and said he was engaging in interstate commerce.
If I refuse to allow you to shop in my store because you won't allow me to check your plastic sacks or shopping cart before you leave and compare it to the receipt, I am discriminating on the basis of....what?