Sue wrote and asked:
"I’m setting up documents in Illustrator CS4 and when I set the page to a size with more than three decimals it rounds it up to two decimals (Example 2.125 rounds up to 2.13). Is there any way it can be changed?"
When working with the inches measurement system Illustrator appears to "round up" when you enter three-decimal precision in the Artboard width and height fields. However, for some reason known only to the programmers at Adobe, this is done for on-screen display only. The 3 (or even 4) decimal precision that you enter is retained. So if you enter 2.125" for the page width, the page will be 2.125" wide.
You can verify this by choosing Window > Document Info, and choosing Document from the Document Info panel menu. You will see the exact dimension that you entered for the Artboard width and height listed here.
(This applies to Illustrator CS3 and CS4, and if I recall correctly, previous versions as well. I don't have an older version handy to test.)