I worked in the accounting department at the district conventions for years (now regional assemblies). We would be in the back rooms and the contribution boxes would come into a room, be emptied in front of several brothers and the sisters with the boxes and put into money bags and brought into the counting room where we had sisters at long tables with different jobs. Some sisters would unfold and straighten the bills (this all includes change too), the next sisters would organize them by denomination (basically counting) and the final sisters would do the final count (final count for sisters that is). Then a couple brothers would recount and they would mark down the amounts by the number of bills (like 10-$100 bills; 45-$20 bills; 20-$10 bills, etc). At the end we would have the money wrapped with the paper wrappers which had the amount printed on it from the bank (I think anyone can get those wrappers; for instance I think each packet of $20s was $400). Checks were handled by a small group of sisters separately from the cash and marked down as well. From there a report was made to the convention overseer and his cronies and they kept a running total of expenses versus contributions. Don't even ask me how much we would take in over a 3 or 4 day convention because I've tried to remember and I just can't.
That's how I remember it being done but that was years ago. Is it the same or similar now?