That's a great point that is definitely worth including! I think that the intent of the rulebook is that you finish your mathematical operation and then round, yes. I think they are either using sum to mean (final product) or in the sense it is used in British English to mean "math equation". Traditionally American English only uses sum to mean the result of addition.
In any case, I would say that my prior logic is incorrect, but I still think that you should round up before doing the logical comparison, since "logical comparison" is not an operation in that Math callout box.