Thanks Nicolas,
I do understand that what I want isn't necessarily what other people want - I'll counter your comment with "please understand that how you label and document a feature is critically important to the usability of your software - you know what it's supposed to do as you wrote it, but we (the users) don't have the luxury of that knowledge".
Separating the various elements of a sale would be very useful (each with their own options). I noticed that even with the include shipping option selected, we have some test data where the total sales value amounts to 0.02 pence (the products, after coupons, were 1p each) but the sales widget reports 0.05 pence total. Perhaps you could publish the formula used in the help documentation and then we could understand what's being added up/taxes applied in what order etc.
Obviously, for a test, it's not that important, but I don't want real data to be over stated by 150%. If this is a rounding error, then it'll only amount to pence - I'd just like to understand it better.