How to apply IIF condition on Grouped total in SSRS Report

Hi All,

I have one condition where Dr. & Cr. are settling the voucher where as the unsettled transaction have either Dr. or Cr.  amount only.

I have created a SSRS report where I grouped Voucher and getting total as zero for every grouped voucher.   

Now i have to assign a Status field in Report design where i need to pass ,0 =  Posted  else Open. Now when i am taking one group total it's going to the grand total of the report and open value is appearing for all.