In most cases the sponsored ad data is extremely high when you have a negative ROI. Go to the Main Menu > Product > Product Dashboard click on the ( i ) icon to open it up to see a breakdown of all of your cost.
Go to the Main Menu > Product > Sponsored Ad Cost use the Smart Search filter to change the date and select the product in question. Once you have the product(s) selected export the data to an excel file by clicking Action > Export These Products. Go back to the Main Menu and click on Reports > Download Exports click the green Download button and the report will export to an excel file. Add filters to your excel sheet and and than use the SUM formula to add up the values.