Some folks on IB pointed out that I'd misunderstood tax laws for online transactions, and after calling up the DRS to verify, it seems that I should not charge tax on transactions, unless the client lives in the same state as myself. The only time I'll be charging tax, then, is when I sell at certain conventions where I do have a license and physical presence. So yeah! Laws! Exciting.
Thanks for thinking out loud on the issue with me, those who did, and I apologize if any of my responses sounded brusque. I have a nasty habit of getting defensive when I make a mistake, and I was already in a mildly bad place mentally the last few days. I do appreciate it though. I've only been doing this on my own for a year and a half, and while I try to stay informed on how to do things correctly, that doesn't mean I always know what I'm doing ^^; There is a lot of information to read and interpret on this stuff.
Hope you're all having an awesome day today!