The case law on this specific topic is convincing. If you are ever in that situation it is usually going to be worth your time and money to assert the right and see it through. Case law supports this. The general maximum “penalty” is being held in contempt of court. And if the government is wrongly persecuting you, it is lose / lose if you divulge.
Do you think this is for fighting parking tickets? It is for journalists to not reveal their sources, whom might be at risk of severe consequences including death.
That's a whole lot more to loose than your money and time.
That's not what we're discussing here, you can't just say "I plead the fifth" and walk away if the people in charge decided you wouldn't walk away, no matter what's right or "legal"
Francis Rawls stayed 4 years in jail despite pleading the fifth all day long
That case also established 18 months as an upper limit. If you are in that situation it is usually better to simply jot divulge. Especially if there is incriminating evidence. Or you are a journalist being harassed by the DOJ. It can only bring you more pain. They will always find something.