Jquery newbie: How can I add up fields in a form?

Jquery newbie: How can I add up fields in a form?

I have a form with multiple fields. ( http://lilbosheep.com/members/pickupB.php) When someone clicks an image field (with class .priceTableBtn) I want it to sum up all fields of class .eachItemTotal and then enter that value into field id #totalOrder

I started out trying to do this with plain Javascript, figured it would be easier in Jquery but I'm new to it. 

This is what I have but it doesn't really work. It puts the value "0000000000" in #totalOrder

$('.priceTableBtn').click(function(){
var tot = 0;
$('.eachItemTotal').each(function() { tot += $(this).val(); });
$('#totalOrder').val(tot);
});
Really, I'd like to take regular Javascript completely out of this entire page's functionality, but I have a due date and need to get it operational asap. 

Basically, when someone clicks an add/subtract image on each row of a table, it de/increments the itemQuantity field by 1, and should both add up the total (itemCost * itemQuantity) and then sum up all the rows for totalOrder. 

Help?

Thanks!