Minnesota uses an open caucus system. This means that you can vote in any caucus, because Minnesota does not require party registration. You cannot, however, participate in more than one caucus.
Additionally, Minnesota’s caucuses offer same-day registration, meaning that you don’t need to pre-register but need only show up at the caucus location on March 1st.
The caucuses are run by the parties, not by the state of Minnesota. That said, Minnesota statute 202A.19 subdivision 2 says:
Absence from work.
Every employee who is entitled to attend a major political party precinct caucus is entitled, after giving the employer at least ten days’ written notice, to be absent from work for the purpose of attending the caucus during the time for which the caucus is scheduled without penalty or deduction from salary or wages on account of the absence other than a deduction in salary for the time of absence from employment.
If you want more information about the Minnesota caucus, got to MN Votes and click on the Precinct Caucuses section.