Nope, although it's a popular myth with other variations, such as "to insure proper service."
There are several reasons why this account of the origins of the term doesn't fly. For a start, acronyms are pretty much a 20th century phenomenon, while the verb to tip is found as far back as the early 1600s and the practice dates back at least to Roman times, if not considerably earlier.
The story to which you refer, if not purely apocryphal, is attributable to Dr. Johnson, the eighteenth century English wit, who allegedly was in the habit of handing over a few coins upon arriving in his favorite London coffee shops. Depending on the account you read, he either dropped them into a box marked "To Insure Promptness" or handed them over with a note attached to the same effect. If there's any truth to this tale, then the good Doctor was way ahead of his time in treating "tip" as an acronym a century and a half before they existed and inventing a witty little phrase as the bogus origin of what was simply a verb.
If that's not where the word comes from, what is the correct etymology of tip? According to the Oxford English Dictionary, the word is derived from the Middle English thieves' slang word "tip," which we've seen variously described as meaning "hand it over" or "to pass from one to another," with the latter version also applying to other uses of the word, such as passing on useful or inside information like a horse-racing tip.
In terms of the more modern usage of the word to mean a gratuity or the giving of such, that was first recorded in the 18th century (back to Dr. Johnson ... )
Just to confuse you even more, another possible origin for the term is from the concept of "khiyuv" (obligation) in Judaism, whereby a seller is expected to "tip the scales" in favor of the customer rather than himself. So if you're buying a couple pounds of bananas, he might throw in an extra one for free.
Tipping practices vary greatly around the world. In many Asian countries it's not the norm at all -- in Japan it's often considered an insult, in fact, while in some instances in other nations it's actually illegal. Western influences are beginning to change this to some extent and tipping's becoming more common in India, for example.
In Europe it's generally discretionary and often not expected (although employers in the hospitality trade will tell you otherwise as an excuse to pay lower wages). When it occurs, it's usually only in more upscale eating establishments, or for services like taxis. From our experience, it's only in the U.S. where tipping is expected in so many situations.
