Discounts to be able to Give Away items

I want to be able to have a promotion where I give away 10 free items (including shipping) to the first 10 people who order from a certain category. But I only want it to apply if there is ONLY 1 item in their cart. I set up a 100% discount including the shipping which works, but I don't want people to get the discount if they have more than 1 item in their cart. Is there an easy way to do this? I have HikaShop Business.

Thank You. I think I will check out the AWO Coupon Pro - it seems like that is a great compliment to HikaShop. I have been quite pleased when setting up the shop. The file upload feature is what tipped the scales for me to purchase the Business edition. Thanks for your hard work and great support. I have another question which I will post as a new topic.