We tip an extra 5% of the bill. Why, because the math is a little easier...I do 10% of the total bill (that's with taxes and first tip included), then split that in half. I figured it's about 25% total, but haven't done the actual calculation yet. We do this when we get great service. On our last trip (returned last week), left this extra for Coral Reef, Concourse Steakhouse, Spoodles, LeCellier, Kona's. We did not leave extra at Cape May and 50s Prime Time, as the service was just adequate at these places.