PHP :: 正規表現 / 少数点第２位までに丸める

$val = preg_replace('/(\.[1-9]?[1-9]?)\d*/e', "rtrim('\\1', '.')", $val);

$val = 12345;      => 12345
$val = 12345.6;    => 12345.6
$val = 12345.67;   => 12345.67
$val = 12345.6789; => 12345.67
$val = 12345.6089; => 12345.6
$val = 12345.0089; => 12345