Payment of rostered days off (RDOs) upon termination involves entering a lump sump during the termination process. Unused RDOs on termination are classified as an ETP (Employment Termination Payment) as shown below from the ATO website.
To enter unused RDO on termination in Lightning Payroll you'll first need to determine the gross unused RDO payment amount (usually determined by multiplying unused RDO hours by the employee's ordinary pay rate). This amount then gets entered on the ETP payout options screen as an Other pay out amount.
These amounts then get reported to the ATO as ETP type O (Other) as shown in the below excerpt from Lightning Payroll's STP Detailed Report.