Without properly itemized gear- you will not get 5/5. You will be able to squeak out 4/5 with skill alone, but the last boss is quite the gear/execution check.
Aerro is absolutely right if you are talking about 16m HM TFB. There is no way to kill the final boss TFB without the best possible itemized gear and augments. Even with the best gear going into the final boss, you will be hitting enrage every time.
8m HM TFB, specifically the last boss, seems to be tuned easier than 16m so you could probably get away with slightly less than BiS gear to get 5/5.