Integrity vs. Career: Can you win at office politics without losing yourself?

I'm struggling with the whole office politics game. On one hand, I want to build strong relationships and advance my career, but on the other, I'm not willing to compromise my values. Recently, I was pressured to support a decision I disagreed with just to stay in my boss's good graces. I stood my ground, but now I'm worried about the consequences. How do you all handle these situations? Is it possible to play the game without selling your soul?