How do I turn down this guy nicely?

OK, I have been very rude in the past to men who constantly pester me for my phone number and dates. I have also been rude to men who just ask me out (I usually just ignore them/ pretend I don't see them if I think they are unattractive or creepy). When I was at the bank yesterday this guy asked me for my number and I politely said "no I do not give my phone number out". Later I ran into him at the drugstore, and he asked me for my number again, so I politely declined again. Today I ran into him at the grocery store, I turned him down again and he asked why I did not want to date him, I said I don't feel I have to answer that for you. He followed me a little longer and asked me again, so I ignored him. If he approaches me again, how do I handle him? Do I continue to ignore him? I don't want to "just be friends with him", because he is annoying, creepy, plus I find him utterly unattractive, I just hate the vibe I get from him. I have been attending counseling to address my rudeness when it comes to interaction with potential suitors, and anger problems. As well as why I should never tell someone my reasons for not dating them. I want to be nice this time, I really do, it's just hard to do when someone won't let up.