When you are setting up a Seller in sandbox account in PayPal, one of the things you have to do is verify the bank account. When you click on the link to verify the bank account, you'll get a page that tells you they have made two small deposits into your account, and you have to enter those amounts in the form to confirm your account.

Of course, since this is the PayPal sandbox and the bank account is fake, it does raise the question of how you are supposed to find the amounts that need to be entered.

Turns out there is not way to get these amounts... but it doesn't matter. Just enter any 2-digit values in the form as the amounts and submit the form. It'll work and your bank account will be confirmed.