why time to move is shorted near the end of the game??

why time to make a move is shorted near the end of the game??
Time to play is 5 minutes. But when the play is near end, the time is shorted, 1 min, then 20 seconds, etc. WHY?

5+8 means that you start with 5 minutes, while it is your turn this time buffer is counting down but after every move you get 8 more seconds.

This is called Fischer delay http://en.wikipedia.org/wiki/Time_control#Compensation_.28delay_methods.29

5 min for the game + 8 sek. p/ move.
Not 5 min for each move :)