Students use splitwise a lot. In their busy schedule its really difficult for them to manually enter bills after group purchases. You can create a system where people can just give in their splitwise id at checkout and they will have the bill available on their app and may be have the items tabulated with option to select who were involved in this product. This involves a lot of work but has a lot of scope. Students might even favor shopping at places that have splitwise support for their groceries. All the data you get about which products people prefer.