Firstly there's no guarantee all five will be on the pitch at the final whistle. Secondly, even if they were, it could go to 6 or more penalties if tied after 5 each.
We should do what the Germans always do, have the entire squad practice, and practice, and practice. And please God, not the Bobby Robson "ok lads, who fancies taking one?" approached that made the Germans (who started practising taking them in kindergarten) laugh their nuts off and beat us every time.