i think it is ok. there are just so many people trying to steal things from the store.
actually, it depends on the areas, some better areas, they will just let you go without check, in some areas, they REALLY DO check everything.
one time, i bought a carry on luggage. the person even open the luggage and check every pocket inside the luggage to make sure it is empty. I paid with American Express Gold Card.
btw, if you know they will check, why you put receipt into your pocket?