Bonus Buy - Buy 10 or more X get 10% off

Hello All -

I have a request for a Bonus Buy to give customers a discount of 10% when they purchase 10 or more of items maintained in a Article Group.

I see creating a bonus buy for the purchase of 10 articles will give 10% for every 10 purchased.  How can we make this to be effective for buying 10 or more??

Thank you for you thoughts