I think I’ve posted a variation of this already some time ago, but this time it is really all about the order of things.
Imagine a perfect world with perfect software, how would order totals look like (if you have all sorts of funny combinations)?
My idea would be:
Cart Total: Total of all cart items
1-n taxable amounts: things, like shipping, etc.
1-n tax: total of all tax for the cart; may be more than one line due to different tax on different things
Cart Subtotal: above cart total plus all taxable amounts
1-n non-taxable amounts: like shipping, gift wrapping, cc surcharge
Total: The real, real total
Anything else? Different??