Can someone who has recently received an SRB bonus tell me how much was taken out for taxes (percentage)?

The guidance from DFAS is 22% for federal withholding. It was 25% but was recently changed in the last few months.
Don't forget to check that your TSP isn't set up to reserve a large portion from your bonus. Some people set that as privates and forget about it years later.

Good grief- federal or fed/state? Figure roughly 20%.