If you have extensive charges to your hotel bill, here is a suggestion to help you quickly review the items to make sure that there are no unauthorized charges:
When signing for restaurant and room service charges, the most likely category of items to be mistakenly or fraudulently posted to your account, tip in an amount that will result in your bill adding up to a number consistently ending in the same digit.
For example, leave a tip that will result in the total bill adding up to a number ending in six: $30.16, $58.46, $71.96.
When you find your hotel bill under your door, you can quickly scan the items for those that do not end in a six. According to Travel Secrets, the odds of an accidental, but legitimate, item on your bill ending in six is 9:1 in favor of the hotel guest.
Via Road Gladiator