It depends. Sometimes all you need to do is click on one of the items and they get grouped together so you can adjust the S&H and send an invoice. That's always a nice surprise.
Many of my customers can't find the button to request an invoice and I tell them to pay for the whole enchilada and after I ship the combined pile I will manually refund the extra postage. That's a hassle because you have to manually add the tracking number to all the additional items being added to the one with the original tracking number.
