Yes!
One option would be to make a coupon link for price X, with Y number of uses.
You can make coupons here:
leanpub.com/YOUR_BOOK/coupons
Here's an article on how to create coupons that might be handy:
You can also make a package and set the price and number of copies here:
leanpub.com/YOUR_BOOK/packages
That way, everybody sees the bulk purchase as an option on your book landing page.
Here is an article about this:
http://help.leanpub.com/en/articles/3287107-can-i-make-a-package-to-sell-multiple-copies-of-a-book