function round_like_php(val,precision)
{
	 return parseFloat(parseFloat(val).toFixed(precision));
}
function sa(thi)
{
	var amount = document.getElementById('amount');
	if(thi.value==0)
	{
		amount.value=0;
		document.getElementById('suby').disabled=true;
		return;
	}

	if(thi.value.charAt(thi.value.length-1)=="."||thi.value.charAt(thi.value.length-1)==",")
	{
		return;
	}
	thi.value=thi.value.replace(",", ".");

	var am = curs*thi.value;
	am = round_like_php(am,0);
	amount.value = am;
	if(isNaN(am)==true)
	{
		amount.value = 0;
	}
	
	if(am>=5)
	{
		document.getElementById('suby').disabled=false;
	}
	else
	{
		document.getElementById('suby').disabled=true;
	}
}