Are the customers doing it? Or coworkers? When I worked at Best Buy, a coworker got fired for just putting their arm around someone while talking to them.
If a customers comes up and touches you to get your attention, that'll be fairly common, and hard to make it stop because you won't see them that often.
If it's a coworker, you have a right to say you don't wish to be touched, if they continue, it can be harassment, because you've now made it known it bothers you.