How do I get my sister to clean my room with me?

okay so my sister and I, we are both 15 (twins) share a room. I live in a 5 bedroom house on the top floor, with 2 empty rooms, and my dad refuses to let me have my own room. But basically, my sister even though she is mature is ALWAYS making a mess. There are bobby pinks everywhere, papers everywhere, she doesn't hang her clothes, she leaves make up tubes on the dresser, she uses products and what not and leaves them lieing around, and disgustingly always blows her nose because she has so much allergies and leaves her snot tissues lieing around the room, it is GROSS. While me, the neat freak, is always always always cleaning our room. I don't think she's ever cleaned our room for at least a year. I get so mad because I'm always cleaning her mess and I have to suffer and do extra work for no reason. I tell my mom that my sister never cleans her room. My mom, always taking the complicated route is telling me that I have to teach her how to clean our room together. She never even yells or tells my sister to clean our room. I keep telling my sister to clean our room together but she never listens and says she doesn't want to and I always feel upset because I do it anyway :( what do I do?