The compass shouldn't be 5-10 degrees out. If it is then it's probably because the pilot has stuck his big metal clipboard on the dash right underneath it, or there are electrics operating that shouldn't be operating if you intend using the compass for primary navigation. The compass card will sometimes have stipulations as to what radios and other equipment should be on or off.
I thought this would be a rant about "what's the point of a compass card which has 1 - 2 degree differences from the compass." If you've tried flying a compass heading you'll know that 1 or 2 degrees is completely irrelevant.