Check out http://www.php.net/manual/en/function.round.php
<?php
echo round(3.6451895227869, 2);
?>
EDIT
Try using this custom function http://www.php.net/manual/en/function.round.php#102641
<?php
function round_up ( $value, $precision ) {
$pow = pow ( 10, $precision );
return ( ceil ( $pow * $value ) + ceil ( $pow * $value - ceil ( $pow * $value ) ) ) / $pow;
}
echo round_up(3.63333333333, 2); // 3.64
?>