var price = new Array(0,99,180,150,130,99);
function cost(k)
{
	if(document.getElementById("check_"+k).checked==true)return price[k];
	return 0;
}
function calc()
{
	var sum=0;
	for (i=1 ; i<=5 ; i++) {sum=sum+cost(i);}
	document.getElementById("total").value=sum.toFixed(2);
}