No need for elaborate drill and kill percentage worksheets. One good problem is worth 10 worksheets. The goal is for your students to be able to calculate a 15% tip in a real life scenario.
You need a menu, a candle.
Split up your classroom in groups of 5 students. two will be on a date the other will be the waitress.
Have each couple order from the menu. The waitress will add up the order by hand and bring them each couple the bill. The couple will then calculate a 15% tip.