If the numbers are in column A, put this in B1 and copy down.
=RIGHT(A!,2)
Then do Copy > PasteSPecial > values on column B to get rid of the formulas.
Then sort on column B
Or, if you don't have the time, space or patience to do that and need to do
this sorting frequently, perhaps Jim Cone's fine commercial Add-in called
"SpecialSort" would do for you. It's available at: http://www.realezsites.com/bus/primitivesoftware/products.php
The 1st thing I thought is: add a new column next to your group and
use a math function MOD(number,100) or even a text function
RIGHT(number,2) there and then sort this new column.
Sorry for my English.