Hi Rachael -
For this credit, all you need to do is track the total amount of waste sent to the landfill and the total amount of waste recycled, composted, etc. You don't need to quantify what percentage of paper or other specific materials go to the landfill for this credit (though you do need to do this to achieve MRc6). Your waste hauler should be able to provide you with information on the total amount of waste, recycling, compost, etc. you produce.