Okay, wow, that’s... strange. I feel your pain on that one. It's like when you're playing flappy bird and you KNOW you're going to make it through the gap, but you still somehow crash. Except instead of pixelated birds, it's money. Maybe some rounding error happening somewhere in the system they haven't accounted for? Or is it possibly adding in some sort of flat fee, even if it's supposed to be waived? Definitely worth digging into the code, I'd say. Good luck!

Tj Wright - Can you create a ticket with support and share the project zip there to test?