Here’s a function for Gaussian/Banker’s Rounding in Javascript adapted from code written by Michael Boon at //boonedocks.net/.

This can be useful if you’re working with Microsoft languages such as VBScript, which use Banker’s Rounding by default in their Round function. Javascript has no built-in gaussian rounding and, instead, uses Arithmetic rounding. For more information on this, see Wikipedia’s article on rounding, specifically, the Round to Even section.

/* Adapted from <a href="//boonedocks.net/code/bround.inc.phps">//boonedocks.net/code/bround.inc.phps</a> Provided under the GNU General Public License Contact me for use outside the bounds of that license --------------------------------------------------------------- This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. The GNU General Public License can be found at: //www.gnu.org/copyleft/gpl.html */ <a href="//boonedocks.net/code/bround.inc.phps"></a> Number.prototype.gaussianRound = Number.prototype.bankersRound = function bround(iDec) { return Math.gaussianRound ( this, iDec ); }; Math.gaussianRound = Math.bankersRound = function (dVal, iDec) { // banker's style rounding or round-half-even // (round down when even number is left of 5, otherwise round up) // dVal is value to round // iDec specifies number of decimal places to retain var dFuzz=0.00001, // to deal with floating-point precision loss iRoundup=0, // amount to round up by iSign= dVal != 0.0 ? Math.floor ( dVal/ Math.abs( dVal ) ) : 1; dVal=Math.abs(dVal); // get decimal digit in question and amount to right of it as a fraction dWorking = dVal * Math.pow ( 10.0, iDec + 1 ) - Math.floor ( dVal * Math.pow ( 10.0, iDec ) ) * 10.0; iEvenOddDigit = Math.floor ( dVal * Math.pow ( 10.0, iDec) ) - Math.floor ( dVal * Math.pow ( 10.0, iDec-1 ) ) * 10.0; if ( Math.abs ( dWorking - 5.0 ) &amp;lt; dFuzz) iRoundup= iEvenOddDigit &amp;amp; 1 ? 1 : 0; // even testing using bitwise and else iRoundup= dWorking &amp;gt; 5.0 ? 1 : 0; return iSign * ( ( Math.floor ( dVal * Math.pow (10.0,iDec ) ) + iRoundup )/ Math.pow(10.0,iDec) ); };