Planning on ordering room service during your next hotel stay? You're going to pay a bit more if you're staying in Las Vegas. TripAdvisor announced the results of the  2014 TripIndexTM Room Service, a cost-comparison of common incidental items and services that many travelers will encounter when staying in a hotel.

According to the study, Las Vegas was found to be the most expensive U.S. city for in-room amenities at an average of $68. Denver was found to be the least expensive with an average of $41.

In its second annual TripIndex Room Service, TripAdvisor compares the cost of in-room amenities in 62 popular cities around the world, including 15 in the U.S. It looked at similar services offered by hotels such as the price of a club sandwich ordered through room service, the dry cleaning of one shirt, and the following items from the mini bar: a bottle of water, peanuts, a mini bottle of vodka, and a can of soda.

"With a wide range of in-room amenities available to travelers, the TripIndex Room Service provides a useful snapshot of what guests can expect to pay for hotel incidentals in cities around the world," said Brooke Ferencsik, director of communications at TripAdvisor. "While 39 percent of U.S. travelers report ordering room service in the last 12 months, only 13 percent said they made a mini bar purchase*, so it's not surprising that some hotel brands have recently announced plans to phase out the mini bar."

The survey also found that travelers expect 22 percent more in the U.S. for in-room services than in other cities around the world. The average total room service cost in U.S. cities is $55, which is a $44 increase from last year. The average for international cities is $45, showing no change.

The most affordable cities for room service include Denver with a $41 average, Seattle at $42 and Minneapolis at $46. The least expensive international city is Tunis, Tunisia.

In the U.S., Las Vegas was found to be the most expensive city for room service with an average of $68. New York was second as the average is just below $68 and Washington, D.C. was third with $62. The most expensive international room service hotels are in Helsinki, Finland, with an $89 average.

The survey found that there is no connection between the price of the hotel and how much room service is. Even though Las Vegas is the most expensive for room service, the hotels are among the cheapest in the U.S.