Buy 1 Oral-B Advantage Toothbrush $2.99
Buy 1, Receive a $1 Register Reward
$2.00/1 Oral B Pulsar, CrossAction or Advantage Toothbrush, any $2/1 from PG 7/4
Pay $0.99, Receive a $1 RR
Final Price: FREE

According to Wild for Wags this RR is Rolling, which means if you did this transaction a second time and used the first Register Reward to pay for the 2nd toothbrush, you will still get the 2nd Register Reward!