How do I tell someone to leave me alone and stop asking to borrow money?

There is this woman at my job who comes in every morning and she was always polite and pleasant. Well I guess she played me for a fool because after a while after coming in she asked if she could borrow 2 dollars. I felt bad so I gave her the money. She stays at a shelter across the highway from my job so I really had no expectations of her paying me back. Now she keeps coming in everyday giving me this song and dance about how she is going to pay me back and then turns around and asks to borrow more money from me! Now this wouldn't be as annoying if all the while she is buying lottery tickets and comes over and tells me how much she won on a scratch off. Why didn't she just give me the money then if she really planned on paying me back? Anyway this 2 bucks is turning out to be more of a pain than I thought it would be. How do I tell her to just leave me alone in a nice but stern way? Other than the constant asking for money she isn't a bad woman or anything. If I tell the managers they would ban her from coming into the store.