This is something I meant to post before. It's the relationship between the raw score and the SAT score for the May 2011 SAT. It demonstrates how much your SAT score will drop with each error.
54 - 800 No errors or skipped problems.
53 - 790 One strike (error).
52 - 760 Two strikes.
51 - 740 You can’t get here for most cases. You round down.
50 - 720 Three strikes - this error drops you 40 points.
49 - 710
48 - 700
47 - 680
For the Student-Produced Response section, you don't get the extra quarter point penalty for a wrong answer and the rounding jump is delayed. Skipped problems will also cause a delay in the rounding jump. However, at some points the roundings kick in. It's a real killer in the 700 range.