I did read one scientific study in 2007 that showed an improvement in student memory after being exposed to rose scent during sleep - however, it only worked if the students smelled the rose odor during Slow-Wave Sleep (not during REM or other sleep stages), and it only worked for memorizing cards, not for memorizing a finger-tapping sequence. In other words, the scent of rose can have a little effect on a specific sort of memory.
The good news is that scents have been proven to trigger memories. Your brain connects smells with whatever was going on when you smelled them. This means that if you have a familiar, pleasant scent in the room where you study, your brain will be more relaxed and can work harder and memorize more easily. My advice is to stay away from strong odors like perfumes - try smells like cinnamon or other cooking spices, evergreen trees, and lighter scents that won't distract you from your work.