When bearing off - there is one checker in the 6 spot, 0 in the five spot, several each in the 4, 3, 2 spots. There are 2 opponent checkers in the one spot. The roll is double 5's. I can't move the 6 down to the one spot as my opponent is blocking that spot. Can I bear off checkers in the 4 spot? If so, three or four checkers?
No, as per the official backgammon rules of the US Backgammon Federation you cannot move in this instance, and your turn is over.
If there is no checker on the point indicated by the roll, the player must make a legal move using a checker on a higher-numbered point. If there are no checkers on higher-numbered points, the player is permitted (and required) to remove a checker from the highest point on which one of his checkers resides.
Since you have no checker(s) on the five point you must make a legal move with those on the six point.
As there are no such legal moves, your turn is over.
You are explicitly required to use the rolls of five only to move checkers on the six point, while those exist.