Formating Numbers

I cant seem to get this to work for me. I want the number to be formated to money (us, 2 decimal points). I have gone through manual, tried money_format, number_format, along with setting the variable, but I cant seem to get it to work. I'm sure it is something simple I am missing. Thanks for the help. <?php $sale_value=$_POST['sale']; $assess_value=$_POST['assess']; $mil_rate=.03965; $ratio=.51; $present_tax=($assess_value) * ($mil_rate); $correct_tax=($sale_value)*($ratio)*($mil_rate); $savings=($present_tax)-($correct_tax); echo 'According to the information you have entered<br />';?><br /> <?php echo "You are currently paying now $ $present_tax<br /><br />"; echo "According to the information you have submitted, your taxes should be $ $correct_tax <br />";?> <br/><?php echo "According to our calculations, a successful assessment appeal could save you annually on your current real estate taxes. <b>$ $savings</b> "; ?>