state tax on US government dividend

WI state (any state?)does not tax US government bond returns or interest. My broker said this is only the case if you own a US treasury bill outright. If you have a money market account which is partially composed of US government securities then those don't count. True? Example: I own a large money market account, and if I look at the composition, it contains: 4.6% US treasury debt, 40% US treasury repurchase agreements, 6% US government agency repurchase agreements. Can does be excluded for state tax purposes?...Thanks