Why do you order five balls for the World Cup?

There were five goals in the penalty shoot-out in the World Cup. The way of penalty shootout in the World Cup is to score goals according to the referee's choice, and determine a team to play first by drawing lots. Both teams have to complete five points, and the one with more goals wins the penalty shootout. If the two sides are still tied after playing for five times, the sixth penalty, the seventh penalty and the eighth penalty will be adopted. Until the final result of the game is divided between the two teams.