I'm the boss, so I make the rules, and my rule is "carry what you want, where you want, within the bounds of the law....just don't carry in front of customers unless you know FOR A FACT that they don't mind". I carry virtually everywhere, but I leave it in the truck when I talk to most customers. Some customers get to handle my rifles, and on occasion my carry pistol. I've taken most employees shooting.
If I were an employee and there was a "no guns in the parking lot" rule, I'd either park somewhere off site or ignore the rule altogether. Laws are different, but the worst that can happen for violating a rule is dismissal.