Charging tax on a tip? That feels… wrong? Idk if I want to say illegal because idk for sure, but it feels wrong.

I just wanted to order hair dye for same day delivery so I can dye my hair without risking getting anyone else sick. I’ve order from Sally’s with same day delivery before and I didn’t notice that the tip amount gets factored into the tax amount. And I know it’s only an extra 41 cents but still, it’s the principle of the thing