As Peter says, it might be a bug. I did another test. Selected the URL from my IDD, opened the Hyperlink panel, clicked on Create New Hyperlink and this is what I get: http://www.projectorcentral.com/paint_perfect_screen_%24100.htm. So ID is changing "$" to "%24". But, when I click on Go To Destination, still takes me to the website! I'm on a PC with CS6 8.0.1 and using Google Chrome.
Did a second test just for fun: without selecting the URL in the ID, I went to Type/Hyperlinks & Cross-References/Convert URLs to Hyperlinks and ID creates two Hyperlinks: http://www.projectorcentral.com/paint_perfect_screen_ and a separate: 100.htm. So, ID splits the Hyperlink right at "$". So definitely ID doesn't like the "$".