just wow...I could have never imagined that a police officer may ask you how much money you have on you? If that happens in my country the answer would have been "why the f..k do you care, or not your business mate" and he could not have done anything about it.
So just to get this clear in my head..In the US if a police officer ask you how much money you have, you are obliged to tell them the truth?
The proper way to deal with this situation is to remain silent, or to ask them why you would possible answer that question. You are not required to provide information beyond ID, registration, and insurance. You should however never lie. They will attempt to catch you in a lie so that they can charge you with a crime, thereby allowing them to search you and your vehicle.
Most of my interactions with police are on foot. I repeat a series of three things in order. Am I free to go? Am I being detained? On what charges? I will provide my name, but never show ID, and never provide any information beyond what I am required. Asking "am I legally required to provide that information?" Is a good way of cooling them down. Most pigs have no idea what the law is beyond the 4 or 5 PC infractions they use on a daily basis.
In a vehicle most interactions go like this. I roll the window down 2-3 inches. The pig walks up and says "could you roll the window down more?" (notice that he doesn't command. He knows enough to ask with authority). I say "No. thats far enough." If he gets cute I remind him that the law requires me only roll the window down enough to be able to hear him. I am being generous giving him 3 inches. I usually get a "where you headed?" at that point. My response is generally to laugh and say "why would I possibly tell you that?" (One pig once got a hurt look on his face and said "to be nice") Then they go for the more direct route. "Got anything illegal in the car?" My response at this point is "really?" If they press, I will simply look at them and say. "I understand your question" If they ask you anything beyond that, just remain silent and look at them like they are retarded.