Price changes as the number of products purchased changes

-- url of the page with the problem -- : www.m2820.com/store/store
-- HikaShop version -- : 3.1.1

I sell books and I would like to make it so the price gets cheaper as they order additional copies of the same book. So, if they buy 1 copy, the price is say, $10. If they order between 5 to 10 copies, the price for that book goes down to $9. If they order 11-15 copies of a single book, then the price goes down to $8 for that book. Is this possible?

I would like to just list the book, then have the price lower automatically depending on how many copies the purchase. Of course, if I have to do it another way, please describe the process in enough detail that I can follow.

Thanks.