Zeustrack also lets you manually modify your campaign cost. Sometimes you may encounter a traffic source that does not provide you with cost details in the URL parameter, that you define when setting your traffic source your postbacks. This is a problem because this cost data is essential to your ROI calculation. 

When manually updating cost data, make sure the cost correlates to what is recorded by the traffic source. If you add cost on a daily basis they should be aggregated for each day you specify.  

To set this up, go to Daily Campaign Report > Cost column.
Specify the time frame, then add the grouping by Date and press the Apply button.

Next, click on the cost number (underlined dots) for a specific day and enter the cost value in the pop-up window. Then press the Yes, change button.