Thanks Nadya. I think I understand the idea now. Coding can get really complicated for me sometimes as it's hard to visualize how to put things in the correct place.
Thanks again!
Max

> You still can use variable. Give this variable sum of each field (either in expression window or as a result of function call).

> If you need sum of this value, just put the same field in the summary band, but check Sum in calculations. If you need to use this Sum in some sort of calculations, you would need another report variable, which would be the same, as normal variable, but with Sum checked.

> Does it clarifies or confuses more? :)