Do you have an age field or formula? If so, you can set up a formula like this:
if {@age} < 6 then "00 - 05" else
if {@age} < 18 then "06 - 17" else
if {@age} < 41 then "18 - 40" else
if {@age < 66 then "41 - 65" else
"65+"
If you leave the zeros, the groups will sort in the correct order. Insert a group on this formula.
-LB