Seems there is some more magic in a Custom Calculation that I just stumbled on from a past post.
See that funky “round up” text in there?
@emre, is there more hidden functionality in Custom Calculations?
I was searching for a method to always round UP to nearest whole number, and I thought that Round Ticket Total Exactly was supposed to do that, but it does not appear to work in a Payment Processor. The example given uses a button-less Calculation Selector …
This exchange rate stuff is starting to drive me insane 
