There are two tax calculation methods. you can either calculate tax amounts per each line item, round them then add them up. Or you can calculate tax amount over entire invoice taxable total.
Due to rounding, these two methods are not producing the same result. Double-entry accounting systems always calculate tax amounts per each line item separate and showing this while you are creating transaction is to serve as reinforcement of what’s happening. This will better match user’s expectations.
Now, I agree, the layout is different, arguably a bit worse because it’s more busy but this will be easy to calibrate in upcoming days.
I wasn’t specifically working on tax calculations in edit mode. It’s just a side-effect of much bigger internal change which will allow me to implement many feature requests easier.