Is a girls rejection final?

Yes, that means that she isn't interested in you. And yes, you should back off.

No, that doesn't mean you shouldn't go to the store (unless you are just going to see her).

Just rent a Ferrari and catch her after work.
That should work, right Max?

💔😞😔

Nothing in this world is final except death and, maybe, taxes,

WRONG first question to a girl.

You should have said, "Hi. My name is ____. I come into this store a lot and noticed you. I'd like to meet you and get to know you. Would you like to go for coffee sometime?"

No I don't think that is teh final rejection, you should try once more because she may be just suffering from heart ache thats why she was just trying to ignore the thing for time being but that doesn't mean she is not interested in you neither this means she is interested in you , you have to make a different approach.

In this day and age, why would a near total stranger give you her number? I agree with Punkey's response as to the way you should have handled things.

The girl's response to you seems very likely a blowoff. You did not ask for a relationship, but simply for her number. She immediately went to the "not ready for a relationship" excuse, so yeah, I think you should back off and forget about her.

As for going to the store, if you need to buy something at that store then go to that store. If you make a habit of staying away from stores where girls who won't give you their number upon first meeting you work, then pretty soon you are going to have to travel great distances to find someplace to shop.