In a way I agree with what @
Hulk said. Very true.
But on the other hand I feel as though it's 50/50. I see it as, if you are good, you get good (generally). If you are bad, you get bad.
For example, you commit murder, you are sent to jail. (Bad karma)
You tell the police about the murderer, you are praised by the police and most likely the victims family. (Good karma, knowing you have done good)