When someone buys a Foody Bag, they can round their purchase up to the nearest dollar. The extra cents go to a good cause. That is the whole mechanic, and it is deliberately small.

Nobody is asked to make a decision about how much to give, or to fill in a form, or to remember to do something later. The choice is a single tap at checkout, and the amount is whatever it takes to reach the next whole dollar. Some people round up by more.

On its own that is a few cents. The point is that it happens thousands of times.

This is the part that makes the feature different from most round-up schemes, where a company nominates one national charity and every customer contributes to the same pot.

On Foody Bag the cause is chosen by the store. The bakery, cafe or grocer decides who their customers' cents go to, which usually means a cause with some connection to where the shop actually is or what the people running it care about.

So the money stays close to the counter it came from, and a customer rounding up at one shop may be supporting something quite different from a customer rounding up down the road.

Two causes have now each passed $1,000, raised entirely in rounded-up cents across many partner stores.

The first was Mens Talk AU, a Perth not-for-profit working on men's mental health, including suicide prevention. The cheque was presented in person at Scarborough Beach.

The second was OzHarvest, one of Australia's leading food rescue organisations, whose vans collect surplus food from businesses and deliver it free to charities that feed people. Food rescuers supporting food rescuers, which is a pleasing way for the money to travel.

A third cause is close to the same milestone.

Giving usually fails at the point of friction. A donation that requires a separate decision, a separate payment and a separate moment of remembering is a donation that mostly does not happen, however willing the person is.

A round-up removes all three. The decision is already in front of you, the payment is already happening, and the moment is now. What it gives up is size: nobody is donating meaningfully in a single tap.

That trade only works at volume, which is why a digital donation tin takes a while to fill and then arrives as a real cheque. A thousand dollars in loose cents is thousands of separate small acts, none of which felt like much at the time.

Small Change, Big Impact moves money. There is a second programme that moves food instead.

Community Share lets a store give surplus food directly to a local cause at no charge, with the cause collecting at a time the retailer sets. No bag is sold and no money changes hands. It suits the food that is better going straight to a group who can use it that evening.

Between them the two cover the two things a food business actually has to give: what it did not sell, and the goodwill of the people buying from it.

Charities, not-for-profits, schools and community groups can register to receive either kind of support. The form asks for the organisation's details, an ABN, a contact, and which of the two programmes suits you.

Being listed does not by itself bring in money. A store partner still has to choose you, which in practice means the causes that do best are the ones with a real connection to a neighbourhood where Foody Bag stores operate.

If this piece has touched on something difficult and you would like to talk to someone, Lifeline is available on 13 11 14, at any hour.