How to convince parents to let me get a pet!!?

I really want a small, caged pet. Perhaps a glider, chinchilla, or bunny. My mom insists on a "NO!" because she simply "does not want an animal" and she thinks it will smell. One question, does anybody know if its true that your small, caged pet will smell no matter what? what should i do to talk her into it?I'm talking step by step instructions. Not just "be responsible" and "beg" been there, done that. I need something that works! Thanks for your help! I appreciate it so much!