It depends on the store manager. Ask them what they will accept.
We have a few employees that have irregular dyed hair.
If you go in without asking, they will probably give you the option of undoing the dye job, wear a scarf or quitting. Guys that wear earings have to wear band aides over the ear lobe.
If it's a darker color they likely won't notice too much. As I know there is one chick I work with that has like a burgundy color to her hair. But in the lights it looks like it's brown. So they let that go. But another chick in Deli deliberately dyed her's purple in front where her bangs are. And they definitely weren't fans of that and so now she has to push her bangs back and under one of the Boar's Head caps.
Depends onyour store management really. I've seen people with green or pink dyed hair and usually if you can cover it in a hat/hairnet it doesn't matter around here. But I would always ask first to be sure.