When I worked at a hometown grocery store, employees with eyebrow piercings had to cover them with a bandaid.

Customers actually complained that they felt the bandaid looked gaudy or promoted uncleanliness (a lot of employees had piercings hence lots of bandaids *laughs*). So the boss changed the rule.

No one ever complained about seeing a piercing on the person ringing them up or bagging their groceries.

As long as an employee isn't flashing a nipple ring, I don't see what the big deal is.