libreoffice calc is foss, reads excel files and has been around for a long time. i used it professionally since 2011 (used open office before that).

If I add up all the costs required that "effectively round to zero" the remainder from a normal salary rounds to zero.

Nonsense, or surely you'll be able to list these costs that add up to, let's say, over 50% of a salary or $30k plus.

(The Netherlands) Pension contributions + employer taxes + office space. First two add up to about 70% on top of gross wages paid. Office space I’d estimate at € 2k per office worker. But indeed, laptops and MS software is cheap in comparison. Bloomberg Terminal comes to mind as a not so cheap software package.