Need assistance or suggestion as to how to figure discount that is based on 1/10th of a penny.

The discount is 1/10th of a penny. So how do I come about finding out

what that discount is for $390,936.47? Do I multiple $390,936.47 by .001

to obtain the discount? Or is there are different number other than

.001 that I should be using. I was provided with the amount as $867.12

as the discount for 1/10th of a penny of $390,936.47. Not sure how

they came up with $867.12. Can anyone assist with this?