Application of tax % when user logged in vs. not logged in

Ok, this question may get a little complicated, so I apologize in advance…

I’m confused about 2 things: user accounts and tax rates.

First of all, when I am working on building my website and am logged in as the administrator, I notice that my shipping address is saved in my profile, even though I have never actually placed an order on my own website. How did that information get saved? There are also blanks for billing address, but no information is saved in those fields.

This discovery was predicated by my confusion / concern regarding tax. I noticed that when I was testing my shopping cart while logged into my site as Admin, the tax showed up in the cart. When I test my site on another computer and am not logged in, NO tax is applied to the cart (it doesn’t even show up), even once I get to the shipping page.

So my concern is this: will tax be added for applicable users (ones in the same state) even if they are not logged in and their shipping / billing information is not saved in the system?

I hope this makes sense… I can clarify more if needed.