I did something very much like this Mark. Heres an extra idea for yours. When someone does donate if you wish to track the amount thats great

But make sure that you include an option in the system with an on off switch per user for those who dont want the amount displayed.
While you as an admin may appreciate every $5 donation that comes your way, they as users may not want to donate $5 if its going to show that they "Only donated $5" Hope you understand what I mean. Its kind of silly, but some folks are really sensative about such things. If you need help let me know.