Grouped Overall Sorting

[Boksberger]

I have a list report that has a set of columns X that are grouped, but need to be sorted by Column Y for both the inner group and overall.

For example, I have the following data

X                Y
----            -----
A               7
A               8
A               10
C               1
B               6
B               5
B               4
C               7
C               3

What I need the output to look like is

A            10
A            8
A            7
C            7
C            3
C            1
B            6
B            5
B            4

I've tried group by column X and then adding Column Y to the group sort, descending, but that doesn't sort on Y within the groups as descending (does ascending instead). If I add Column Y to the detail sort, the overall sort changes to Column Y and the lowest value represented by Column X dictates where in the sort Column X is.

i.e.:

A            10
A            8
A            7
B            6
B            5
B            4
C            7
C            3
C            1