I think this large issue/project/epic will tackle this:
the database does not store taxes by line - when they are not included in price. So its a bigger project to create that stored data, rather than ‘simply’ making sure it is pulled onto an invoice.
But I’m not 100% sure. I think @Rachel and @Jana might have a better understanding of the scope than me right now but you certainly make sense objectively to me but I’ll for sure need to see this process in play. Rachel is often able to show me and Jana how instance managers do processes like what you describe.
Thank you so much for the video! This is so so so helpful for us (design and product) to understand how real people use OFN for real cases! I’m over the moon! 
< That’s the cow jumping over the moon…i hope that’s a reference people know haha!