note 21436 rejected from function.round by sander

This was taken from the MySQL site. I suspect the same applies to the PHP round function. Note that the behavior of ROUND() when the argument is half way between two integers depends on the C library implementation. Some round to the nearest even number, always up, always down, or always toward zero. If you need one kind of rounding, you should use a well-defined function like TRUNCATE() or FLOOR() instead.