Why is my Base report builder replacing my default zeros (from query) with NULL?

I have an expense database I created for a client where on the form I set tax fields to default to zero so that I don’t end up with NULL values when I try to do my calculations. I created a query to pull together all the information - it all looks great in the query - all my zeros are in the tax columns where they should be and all my calculations within the queries work fine. But then I create a report with that query and the report replaces all of my zeros with NULL and now none of my calculations are working.

I have already posted questions about how to get the report builder to insert a zero where there is a NULL and have not come up with any solution for that either.

Any help would be greatly appreciated.

It seemed that peculiar problem resolved itself. I have found that LO Base Reports built using the Report Builder extension behave very differently at times depending on which version of LibreOffice you are using and what operating system you are using it on, and every now and then even with the same version on the same OS!. Its really my only complaint I have about Base… But I have found that my base reports on the newest LO work quite well, and have updated everything to that.