This is America. Land of the free, home of the brave. Where every service has a magical, unspoken, aggressively expected charge written at the bottom in fine print. 

As socially regulated a transaction as it may be, don't forget - it's at your discretion. 

Who should you be skimping, and who should you be loading up? We've the everyday, real person, socially smart, no-nonsense guide to "graciously" navigating gratuity. Pick your battles and invest wisely.