Sometimes if you get tired of refreshing your "today's earnings" without seeing a change, try switching between "Last 7 Days", "This Month" and "Today".
I've noticed that sometimes one of these views is updated ahead of the others - there doesn't seem to be any consistency - if I have left the view on "today" for a while and haven't seen any changes, I switch it to "This Month" and the earnings will have updated, and if I go back to "today" it is usually still at the early earnings figure.
Anyway, if you get impatient to see your earnings report update, try looking at your report from a different time reporting... :)
I suspect the caching is done at Google's end; with the number of publishers surely the account records are on more than one server, and updating all servers takes some time.
Just the other day, I checked my "Today" stats, and they were a number of dollars lower than when I'd checked them earlier. They went up again when I reloaded the page, so it was pretty obvious that I'd just hit a sluggish server.