MySQLs approximate value types are evil :)

Don't use MySQLs approximate value types like float or double anymore. Instead use decimal(15,4). If you need more precision or scale, then you can always extend this class.

References:
http://dev.mysql.com/doc/refman/5.5/en/problems-with-float.html
http://dev.mysql.com/doc/refman/5.5/en/precision-math-decimal-changes.html