So how does it work? Oval users achieve savings using commands that tell Oval to make a deposit into the app’s secure digital savings account each time there is new income or spending in a linked account. Oval says the system is based on the latest research from financial experts and behavioural economists. Users are to make financial decisions through a combination of technological solutions and the suggestions and advice of other users. There are three types of programs: round-ups that save the spare change from transactions, percentage saving that puts aside an amount equal to a fixed percentage of a transaction or income, and fixed amount saving which saves an amount chosen by the user each time a transaction is made at a specific merchant or on a specific category or user tag.

https://techcrunch.com/2017/04/05/oval-combines-tracking-saving-and-investing-into-one-app-driven-by-ai-and-you/