Conditional Number Format On Specific Matrix Column Group

I'll try to make this simple. I'm on SSRS 2005 and I have a report with a matrix object that has one row group and one column group. I need to switch the number format only for values where the column group has a specific value.

For example, here are the records in the table:
Customer, Type, Amount
Customer1, Revenue, -100
Customer2, Cost, 60
Customer1, Revenue, -200
Customer2, Cost, 125

By default the matrix object shows the following (the total comes from the standard subtotal on the column group):
Revenue Cost Total
Customer1 -100 60 -40
Customer2 -200 125 -75

But the users need the report to look like this, with all positives (why, oh why?! ):
Revenue Cost Total
Customer1 100 60 40
Customer2 200 125 75


I was able to use the inscope function to switch the signs of the Total numbers. But now I need to switch the signs of the Revenue column from negative to positive (and vice versa), without affecting the signs of the Cost column. It's strange to me because I CAN switch the signs for a specific row group (changing Customer1's number format, without affecting Customer2's format) using something like this:

=iif(Fields!Customer.Value = "Customer1", "($#,###.#0); $#,###.#0", "$#,###.#0; ($#,###.#0)")

But a similar expression specifying a column group value does not work, because the report seemingly doesn't recognize the value of the column group at all no matter what I do:

=iif(Fields!Type.Value = "Revenue", "($#,###.#0); $#,###.#0", "$#,###.#0; ($#,###.#0)")

The other reason why this is strange is that I've done drill-through reports off of matrix objects where specific column group values (the ones clicked on) can be passed into the drill-through report parameters. So it recognizes the column group values upon drill-through, but not for formatting?

How else can I do this? I must be missing something here. Thanks.