Add a 0 to the end of a decimal number to make sure it's always 2 decimals?

I am using the following code to work out an inc and ext VAT price:

$('#totalexvat').text开发者_Go百科(totalprice);
var vat = totalprice / 100 * 17.5;
vat = roundNumber(vat,2);
$('#totalincvat').text(totalprice-vat);

Sometimes I get .3 or .9 instead of what I would like to be .30 or .90 because it's money, is there a way to do this?

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You may want to look at this: http://code.google.com/p/jquery-numberformatter/ since you're using jQuery already.

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try toFixed