Uber adding option to tip drivers

SAN FRANCISCO - Uber will soon enable customers nationwide to tip drivers with just one touch of their smartphones.The new tipping option is coming as part of the ride-sharing app's latest update.Passengers can either choose from a selection of preset tip amounts or enter a custom amount. They will also be able to add a personal note for their drivers.As of Tuesday, only a few cities in North America have implememted the in-app tipping. By the end of July, passengers in every U.S. city will have