jquery calculate the sum of products x Quantity
<p>I use this code to calculate the sum : <a href="http://jsfiddle.net/QmTNZ/2/" rel="nofollow">http://jsfiddle.net/QmTNZ/2/</a></p>

<p>I want to modify it, to show 0 when there is no valid quantity or it is empty and not "NaN"</p>

<p>I want also to format the Sum to have only 2 numbers after the comma.</p>

<p>Help (I'm beginner in jquery).</p>
