What do I do?

Im a female and this cashier (woman) who is married keeps staring at me smiling and always says hi and waves at me, tells me im her friend, she asked me my name I told her and she was like, "i like you" while im in line with other people, and now that she knows my name she teases me, shes like "Sashaaaaa" while shes working, and if I respond she'll turn her head and watch me and she starts smiling.

Some stores train their employees to be overly friendly and some of their employees don't know how to separate their job from their social life. Who knows what that's all about. If she makes you uncomfortable, tell her to knock it off, you don't want to listen to it or talk to the manager or shop at another store. You are entitled to choose your own friends.

I wouldn't think anything of it unless she made an overt pass... unless of course it makes you uncomfortable.

Nothing to worry about, unless it gets psyisical