A friend is a coffee roaster and at dinner this eve ran me through the coffee value chain and how little the farmer (typically in South America) participates/benefits. He has an idea to start promoting a small, discretionary, additional contribution from coffee patrons at cafes when they pay for their coffees. They would have the option to pay (for example) $4 for their coffee or $4.05 and the $0.05 would go to the farmer. I immediately thought the lightning network would be ideal for this, the payment could be split at the point of sale. What would be the best way of implementing this currently?