Quickbooks 2003 had the ability to progress invoice.  Yeah, 20 years ago.  QB online is geared towards a coffee shop. 

My workaround has been to only invoice quantities of 1.  If the order is for 7 I put "set of 7" in the description and the quantity is 1.  That way I can bill .1 and it is easier for clients to see it is 10%.