I can't help you with the dunking part, but what one of my basketball coaches made me do to get a higher vertical was to jump rope. You need leg strength to be able to jump, so like John said, squats are good, but don't forget about the rest of your legs. Make sure you are strengthening you calf muscles. My coach made me do 500 heel raises each day. Also, rim touches (or in my case, backboard touches) are also pretty good at strengthening the legs and making yourself more explosive.
Plyometrics(box jumps, depth jumps, progressive line jumps/hops etc..)
Olympic lifts(dead lifts, cleans and snatches)
Its not just strenght its also technique. One thing you need to learn/do is generate strenght from your hips and ur posterior chain. Olympic lifts, deadlifts and squats next to pylo work. Wil help you to understand the movements and at the same time developed strenght were needed.
I do track and field... (6'1" and I do the triple jump) the 4 best vertical jump (and lateral jump) exercises are box jumps (increase height and reps continually) star hops, (Google them) rope jumping, and a lateral (side to side) jumping over an object. (Increase height of object weekly)
If your 5'5 is possible that this will work for me??