Need helps on product pricing

I have added 10% agency commision on total product cost but when I calculated the 10% agency commision on total order amount there is a difference in total agency commision how do I adjust that difference

For Example :

Product Cost : Rs. 100

Agent Commision @ 10% : Rs. 10

Net Product Cost: Rs. 100+Rs10 =Rs110

But  have to give the commision on Net Product Cost which is @ 10% is Rs. 11 but I have calculated the commission of Rs. 10 and now giving the commission of Rs. 11 to agent so I have a loss of Rs. 1.00

Can anyone suggest me how I Calculate the agent commission in a way that I dont have any loss.