You can land with almost zilch in the tanks (not smart). The :45 fuel reserve and fuel to alternate is for dispatch. IF you land with below company emergency fuel someone is going to talk to you no doubt (FAA or company)
Remember too.. min fuel means NOTHING to ATC. It gets NO priority handling and no special treatment from ATC. Emergency fuel puts you at the front of the line. Also, you may NOT be informed if ATC decides to declare you Emergency fuel.