I can certainly relate - DD1 is 9 and an all around great kid - well everywhere but at home! She's not horrible at home, but certainly tries to push the limits as far as she feels possible! My latest tactic - "If you act like this again, I will write a letter to your teacher and the principal telling them of this behavior" She's completely horrified of that thought. Hummm?
We have gone around and around about why she feels she can act and speak to us (DH and I) is such a rude and sassy manner - she certainly would never speak like that ANYWHERE else.
All I can figure out is that she a pretty much a normal kid - who pushes the limits to see how far we will go.
My advice is simply said and hard to follow - stand your ground, know your boundries and stick to them.
When a boundry is broken, you have to decide what will be done.
Keep trying different tactics too. If one doesn't work or has lost its effect - think of something else.
DD1 amazed me the other day, when she told me we needed to fill her hat with more ideas. This was an idea we used when she was about your daughters age. We would fill her hat with different responses, actions and ideas for situations where we wanted to help her improve her responses - to act not to react. For example - when she would get angry - she would want to storm away. We would stop her and ask her to pull something else out of her hat. She could choose things like "I'm really upset right now and would like to take some time on my own to think about it." or simply "I'm mad and upset. I don't want to talk" We haven't really talked about "the hat" in awhile, and all of a sudden, SHE states we should work on filling it up with ideas again!

As we were talking I realized what a wonderful this tool really is. Here we are talking, her leading the discussion, and she is telling me about situations she needs help with - at home and at school. Wow - what a way to stay connected.
I hope some of this helps. Hang in there - everyone keeps saying - ITS JUST A PHASE - hummmm OK!