If the player is inside of a building they own and it is open for business, if a customer makes a purchase maybe have some kind of indicator showing how much each customer is spending on that transaction. This would allow us to get an idea of how much money the business is bringing in that day without having to wait for the end of day report. Also it would add some nice visual eye candy to the game if done right.
I was thinking a nice animation with some small green text like “+$5” could appear above the current customers head, floating upwards and slowly fading away.