Lots of good information here. Three things to remember:
1. Shooting groups is intended to help you develop good form (it shows when you do things wrong).
2. The five inch number comes from the size of a pie plate or paper plate, which is also approximately the size of a whitetail deers vitals. If you can consistently put all of your arrows inside that paper plate sized area at a given range then that is a good max range for you to hunt with.
3. Keep practicing until you get down below the five inch group or target, say to three inches. That way when the constant challenges we face in hunting situations occur you will still be able to make the five inch shot.