Utility method to round to specific precision

@param

I thought I would share this here as I suspect many of you could use a method to round values to a specific precision (e.g. 2 decimals for currency)
http://www.pmddirect.com/wp/?p=427

If you don't want to check that link, here is the code for the method:

 /**   * Rounds the supplied value to the precision specified by the precision parameter   * @param {Number} value The value to round   * @param {Number} precision The number of decimal places or precision to round to   * @return {Number} The rounded number    */  if(!Math.roundToPrecision)  {      Math.roundToPrecision = function(value, precision)      {          Guard.NotNull(value, 'value');                    b = Math.pow(10, precision);          return Math.round(value * b) / b;      }    }