When you rotate the tires do you have to do the wheel alignment as well?

NO! When rotating the tires, look closely at the tread. If you see any abnormal wear, such as uneven wear, feathering, or dipping. Have an alignment performed. Otherwise just rotate. Toe adjustments are common, and is the fasted tire-eating adjustment. An alignment should be checked every six months. If it's not out more than .04 by then, wait longer between alignments. The older a car gets, the faster alignments go out. A reputable place will give you a before and after print-out of your specs. And will check it for free.