You're absolutely right. I was being an idiot, I work in units of pt, but when I open inkscape it's in px, so when I selected two lines and got the percentage, I would change the units back to pt and the number would change since I didn't realize I was initially in px. After this all my units would ...

I don't know what I'm doing wrong. I'm chaning the stroke width on one of my lines and all of the lines will be propotionally changed. This has something to do with me selecting a line and another line of different stroke width. If I change the units for stroke width with out changing the number ALL...