Thanks Raul. You solution does what I want at the month level, but when I expand the next dimension it does not.
See the screen shot attached. When I expand the first two months, for the first month (date in the red box), the Month and YTD should have the same value for each Cost Center. For he second month (highlighted yellow), YTD should be the sum of months 1 and 2 for each Cost Center. For example the YTD total for CORP LOGISTICS in Month 2 should be $104,454 + $120,310 for a displayed total of $224,765 with rounding.