This isn’t a new idea but it would be a fantastic tool to help people save.
For every transaction you make the cost would be rounded to the nearest pound up and the difference would be transferred into a savings account. Perhaps a Monzo ISA 
Some of us use moneybox to save the round ups into an ISA. Theres also an integration between moneybox and monzo, if you want to help test it send me a message 
I would love to help test, please instruct on the next step.
It isn’t 
(but that’s ok) & it would be awesome!
If you’re interested in seeing the other ideas that users have had for this feature, this is the best place to start…
There are dedicated topics for Moneybox, Chip & Qapital too, including a potential community user built Moneybox integration.
If you DM me your userId (can be found at https://developers.monzo.com/), I can add you as a collaborator.
Only started testing this with others yesterday so any other testers would be great!