Going by ticket sales (gross/ average price) it's 5th, it's also 5th in . But it doesn't matter, it still made a lot of money and ticket prices did not go up by anywhere near the $2 you said (19 cents since 04), so all your statements are wrong.
In-theater movie viewership in the US has declined every year for the past 50 years....you can't refute that. By saying Pirates 2 is the biggest opening in terms of dollars is not the same as saying it is the biggest opening in terms of tickets sold.