How do I handle my dad?

You could start by talking to your sister and telling her that she needs to speak up about what she did. You covered for her, now you are in trouble. Are you beginning to see a pattern here? Lying is not the right thing to do when dealing with your Dad. He's going to take as, you didn't learn your lesson the last time, so maybe bigger punishment this time? Also, you might want to talk to your Grandma. She might be able to help difuse the situation.