I think you'll save about 15-18$ each. 
There are 5 US orders and total weight would be 2.6 kg so 3 kg weight which is about $64. About $13 each split amongst the 5 orders.  About $14 to ship within the US? 
I don't mind either way.  Not much more work for me but if no one else speaks up, I'll just go ahead and skip this.