i think in actual practice you will rarely get contempt for refusing to testify or taking the fifth for questions that could only tenuously implicate yourself in practice.
Usually if you let the prosecutor know up-front that you're not willing to cooperate they will tend to save themselves the hassle of trying. It can go wrong if they subpoena a belligerent witness, then they don't turn up on the day they're supposed to testify, and now the jury is empaneled and they start doing a dance where they demand the sheriff finds the witness, but then the clock runs out on holding the jury and it's a mistrial all round.
