I carry two pocket knives on me (one for box cutting and one for larger cutting tasks). I used this combination for two years before I got a talking to about them from one TL. I ignored her talking to because she's literally the only one that cares. My STL doesn't even care. There are a few reasons why I don't like box cutters. They're dangerous, especially because the one's we're provided open and close freely. At the same time they still dull fast and finding a new blade is a pain. I often lose them too, or other tm's borrow them or don't give them back. My knives only open when I want them to, I can touch them up on a grind stone when they get dull, and because they're $40 and $100+ dollar knives respectively, they don't get lost, and they sure do get returned when I loan them out. I'm careful with knives anyway. I can count on one hand how many times I've cut myself ever.
So, officially, you're not supposed to, but more than likely nobody at your store will care. If you cut your finger off though, they aren't liable, so don't cut your fingers off.