According to the pilot, he flew a "normal" approach to the helicopter pad, then hover-taxied to the parking area. Two other helicopters were parked at the far edges on opposite sides of the parking area. Following a procedure that had been developed over the previous 10 years and executed over 20 times without incident, the pilot hover-taxied into the center position and began a pedal turn to align the helicopter with the others. About 90 degrees through the pedal turn, the tail rotor of the pilot's helicopter contacted a main rotor blade tip of one of the parked helicopters, resulting in substantial damage to a tail rotor blade. The pilot completed the pedal turn and landed uneventfully. The pilot did not report any preexisting mechanical anomalies that would have precluded normal operation.