This has been very helpful.
I'm wondering if you could include that change in the repository.
It won't hurt programmers that use two decimals I think, but it'll be of great help for those that need it.
I think there's the same issue with coupon codes - I created a 10% off product summary coupon code, here's the result:
Products Total € 101.99
Shipping Total € 26.62
Coupon Code - € 10.20
Order Total € 118.41
As you can see, the discount should be 10.19, but some rounding is happening somewhere.
This is not a big issue, but since we're talking about it...