When you are on Fidelity, click News & Research, Mutual Funds. Then screen the funds to only money market funds, Fidelity funds only, require less than 2.5k initial investment, you get 11 funds in the list.

Switch the view to "Daily pricing / yields" to see the 7-day yields. Sort by this 7-day yield.

Apply the "50% rule" (If a fund contains less than 50% of the thing that makes it tax-exempt, it is completely not tax-exempt). I know only FDLXX has >50% in US Treasury and US Gov Obligations. All of the funds above it in the list are dominated by Repurchase Agreements, which are not state tax exempt.

Then it's just a matter of multiplying the numbers. Example: 4.54% x (1 -0.24 -0.093) = 3.03%