I have dropped whole boxes of eggs a couple of times, on the floor, rolling all over the room. 100% hatch rate.

That is a wives tail that originates from a tiny fact. If you rotate a turtle egg at a specific time in incubation you can cause the head to split in two, hence all the two headed turtles available every year. Other than that, it is nothing. Your eggs will hatch if they would have without the rotation.