Altering the Displayed Format of Numbers to the Nearest 100

Frank asked if there is a way, using a custom number format, to round the display of numbers to the nearest 10, 100, etc., without affecting the original numbers.

The answer is that there is a way, and there isn't a way. (Don't you love those answers?) There are custom number formats that allow you to round the display to the nearest thousand or the nearest million, as follows:

[<=500] "0";#,"000"
[<=500000] "0";#,,"000000"

The first format will round to the nearest thousand, and the second will round to the nearest million. If you are looking for a custom format that will round to some other power of 10, you are out of luck, however. In those instances, the best solution may be to simply create another worksheet that uses formulas for rounding and uses the contents of the original worksheet as the source.