For tax exempt mutual funds that are not state specific, more than one state, enter the MORE THAN ONE STATE option.
....or for the "Online" users, you go to the bottom of the list and select "Multiple States".
But if you are not a resident of CA, MN or IL, (or not a resident of any of the sates without an income tax) you might be able to lower your state taxes some.
If you break down the $$ received from Bonds issued by your own State, and any US Territories (Puerto Rico, Guam etc), that can lower your state taxes. But for a mutual fund, box 12 usually has to be a pretty big value to start with.
Example: If you had $1000 in box 12 of a 1099-DIV form, and all was from your single Mutual fund. IF the separate info from the fund indicated that 2% came from your own state's bonds, that's $20 from your state and $980 from all others. If your state taxes income at ~5% for that $20, you saved a whole $1 in state taxes....big whoop! And if other funds fed into the box 12 value on that 1099-DIV form, then you need to make the calculations separately for each fund.
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If you do decide to do a breakdown, you only specify your own state and any US Territories...all others are lumped together as a single "Multiple States" entry. Like below for an NC resident: