Let's start with the law.
Minnesota statute 626A.02 makes it legal to secretly record a conversation to which you are a party as long as there is no criminal or tortious intent. You do not need the consent of the other parties to the conversation.
As for an employment setting, I suggest you do it secretly and never let the recording see the light of day unless you need it as evidence at some point after your termination of employment.
Your boss is not likely to allow the recording and could conceivably fire you for doing it, or even asking to do it. Piss him off sufficiently and he could report the cause of your termination as misconduct and make you ineligible for unemployment compensation.

