Whenever you shop at a company that's not supported by the Grifin app, you will automatically put $1 into your cash fund. So, what can you do with this cash?
Any cash sitting in your account earns interest. You'll see your earned interest added to your cash fund on monthly basis and be able to track it through the "Reports" section of the app.
You can also use your cash fund to purchase more stock in the companies you currently own. This can be a helpful tool for balancing out your portfolio.