Thanks, I was able to get it to work by adding a timer complete event with the reset:

Code:
var addTenPointsTimer:Timer=new Timer(500, 10);
var currentScore = 0;
score.text = "0";

function addTenPoints(event:TimerEvent):void{
	currentScore++
	trace("add point");
	score.text = currentScore;	
}

addTenPointsTimer.addEventListener(TimerEvent.TIMER, addTenPoints);

function tenPointButton(e:MouseEvent):void{
	addTenPointsTimer.start();
}
tenButton.addEventListener(MouseEvent.CLICK, tenPointButton);


addTenPointsTimer.addEventListener(TimerEvent.TIMER_COMPLETE, endAddTenPoints);
function endAddTenPoints(e:TimerEvent):void{
	addTenPointsTimer.reset();
	trace("Timer is reset");
}