I am building a simple converter, converting between mm's and inches and I need to round off the results to 2 and 3 decimal places respectively.
The code can be seen below can anyone show me how to get my results with decimal places:

<SCRIPT TYPE="text/javascript">
function popup(mylink, windowname)
if (! window.focus)return true;
var href;
if (typeof(mylink) == 'string')
window.open(href, windowname, 'width=400,height=200,scrollbars=yes');
return false;

<script language="JavaScript">
function mmConverter(){
document.converter.inch.value = document.converter.mm.value / 25.4
function inchConverter(){
document.converter.mm.value = document.converter.inch.value * 25.4
<p>Just enter the amount in either box and press enter or click the convert button<br> to display the conversion in the other box</p>
<form name="converter">
<strong>mm(s):&nbsp&nbsp&nbsp</strong> <input type="text" name="mm" onChange="mmConverter() "><br /><br><br>
<strong>Inch(es):</strong> <input type="text" name="inch" onChange="inchConverter() "><br /><br><br>
<input type="button" value="Convert!" /><br><br><br><br><br><br>