I started using Acorns for shit's and giggles last Sept, a competitor to Stash. Acorns Roundup feature (ie. Spend $3.27, Acorns rounds up to $4.00 and invests $0.73) was easier to understand on paper than Stash's smart save so went with Acorns. Acorns will aggregate all your roundups and withdraw once you hit at least $5.00.
Since Sept, I found myself saving an additional $100/mo with virtually no effort and no noticeable impact on spending behavior. Second most aggressive etf and am up 10% give or take.