Both of my boys roll around but for different reasons.
When Son #1 begins to roll, it is out of sheer exhaustion. His steps to rolling around on the floor are as follows:
Step 1: Run around like a chicken without a head. This helps keep Son #1's eyes from closing when he is sitting still. Running around like a chicken without a head might include some Slow Mo Football action (see post from a few days back).
Step 2: Hop like a cricket from couch to couch. This usually attracks the ire of the parents and eventually gets Son #1 in trouble.
Step 3: After sitting in timeout for hopping like a cricket, rub the eyes. Slump up against a piece of furniture on the floor and slowly sink down to the floor until laying down.
Step 4: In order to keep from relaxing, frantically roll around on the floor with eyes half closed. This is usually the last ditch effort to keep awake. When Son #1 was younger, the rolling was usually followed by screaming. Finally, fall asleep mid scream and roll.
Son #2 tries to roll to see what is behind him. His steps to rolling are as follows:
Step 1: First, turn head to see what is beside you. Hopefully, it will be a bottle, a boob, or a toy.
Step 2: Upon discovering it is a toy, try to touch it. Roll onto side by pushing with feet.
Step 3: Fall back over and repeat Step 2.
Step 4: Get from back to tummy with a helpful nudge from parents. Look around with a mixture of joy and surprise.