Gratuity is before tax now you can use your grade school math skills to calculate the sales tax rate they paid. Ah who am I kidding I'll do it for you.11.99 * 1.2 = 14.19? Tip the waiter because their boss is obviously an idiot.
The bill was for $11.00 and they paid a sales tax rate of 9% for a total of $11.99 add $2.20 for the 20% tip and new total is $14.19 just like the dumb boss said. Now get back out there and wait on the tables and leave the thinking to others.