Gross Taxable Total can be seen on transactional Reports, for example, the Payroll and Transaction Report. It is calculated by totaling everything that is before tax.
Pay Components (Normal, Overtime, Leave, Termination Components, etc) + Additions Before Tax - Deductions before Tax
It differs from the Residual Gross in STP Reporting, which is the total of all components and additions that have Gross as the STP Reporting Group.
Total Cost can be seen in several Reports, for example, the Payroll and Costing Reports. It shows the total cost of the employee(s) to the business and is calculated by totaling all the earnings and superannuation.
Pay Components (Normal, Overtime, Leave, Termination Components, etc) + Additions Before Tax + Additions after Tax + Superannuation