Sundays do count, but the studios have a system based on statistical principles which allow them to accurately perdict the gross. They are usually only off by a few thousand at most. So the official weekend tally is a very robust 27.8 million!
# Title Jul 20 - 22 Jul 13 - 15 % Chg. Theaters Weeks AVG Cumulative Distributor
1 I Now Pronounce You Chuck and Larry $ 34,775,000 3,495 1 $ 9,950 $ 34,775,000 Universal
2 Harry Potter and the Order of the Phoenix 32,185,000 77,108,414 -58.3 4,285 2 7,511 207,541,000 Warner Bros.
3 Hairspray 27,800,000 3,121 1 8,907 27,800,000 New Line
4 Transformers 20,506,000 37,027,901 -44.6 3,762 3 5,451 262,969,000 Paramount
5 Ratatouille 11,008,000 18,012,196 -38.9 3,402 4 3,236 165,628,000 Buena Vista
6 Live Free or Die Hard 7,300,000 11,279,135 -35.3 2,727 4 2,677 116,466,000 Fox
7 License to Wed 3,760,000 7,311,297 -48.6 2,525 3 1,489 38,678,000 Warner Bros.
8 1408 2,600,000 4,934,516 -47.3 1,451 5 1,792 67,500,000 MGM
9 Evan Almighty 2,455,000 4,895,055 -49.8 1,779 5 1,380 93,469,000 Universal
10 Knocked Up 2,318,000 3,676,500 -37.0 1,288 8 1,800 142,724,000 Universal
http://boxofficeguru.com/weekend20.htm
....but the world goes 'round