Itemize uses a number of data points as it considers tip presence. A merchant’s category, e.g. Dining & Entertainment, Taxi & Car Services, etc., can help indicate whether a given merchant might accept tips. Common tip phrases, e.g. tip, gratuity, service are also considered.
If a tip is thought to be present, the document will be forwarded on for an additional layer of processing, where a tip value will be extracted and the grand total value updated.