It’s standard etiquette in the United States to leave a tip for your server at a restaurant, but if you took the word “pourboire” literally, you might think a gratuity was only for drinks. The word, which comes from French, translates literally as “for drinking.” However, if we look to Emily Post for guidance, a wait service tip should be 15% to 20% of the bill for both drinks and food, though it’s OK to tip on the pretax amount. For a pourboire on drinks alone, meaning at the bar, she suggests giving $1 to $2 per drink, or 15% to 20% of the total bill.