If you don't want to use a stepper, which is the absolute perfect solution to your problem. you could use a servo motor. But that requires some feedback mechanism. If you just cut off the supply to a simple DC motor, it's going to coast a bit, depending on the mechanics of your system; it is definitely not going to be precise. You could use an electrical break circuit. There are several methods; for example: switch the power leads of the motor to a load; apply a reverse voltage.
A lot of this depends on the actual accuracy requirements of your system.