Rounding to millions and displaying "-" when there is no data in cell

Hi

I am trying to round the data in my report to millions E.g.( 2,735,933.74 needs to be displayed  as 2.73) I used the Custom in excel formatting which is #,###.00,,;-#,###.00,,

Initially I had selected Accounting as format which displays a dash in cell which has no data. when I change the format to custom it rounds up to millions but for cells with no data it displays as".00"

I want the data to be rounded to millions and a dash to be displayed in cells which has no data. Can somebody please help??? I am working in BPC 7.5

Thanks!!!!