When I first began Aikido I also became dizzy after performing multiple rolls. Just like anything else you learn in life, rolling becomes easier the more you do it. So, the more you roll the less dizzy you will become over time. You get dizzy because the semi-circular canals in your ears (they help you keep balance and detect motion) are not giving your brain the same inputs as your eyes. It is very similar to the mechanism that causes motion sickness when riding in a car. If you are a passenger in a car and are reading a magazine at the same time you may become car sick. The reason is that the semi-circular canals in your ears are detecting the motion of the car, but your eyes are focused on the magazine (they are not detecting any motion). The result is motion sickness. If you look up at the road and scenery as it passes by, the motion sickness usually goes away. The same works for rolling. If you keep your eyes closed while rolling, your only getting half of the brain inputs you need, hence you experience dizziness or motion sickness. The simple solution is to keep your eyes open. Focusing on one "spot" like NYFE Man suggested will also help (that's how people get over sea-sickness, they focus on the horizon). And of course, just as MJ suggested you should practice rolling as often as possible; by doing so, your body will become acclimated to the rolling motion and your dizziness will decrease. Have a good day!