Since the emergence of Content Centric Networking (CCN) as a new paradigm for content delivery in the Internet, copious of research targeted the evaluation or the enhancement of CCN caching schemes. Motivated by providing the Internet Service Providers with incentives to perform caching, the increasing deployment of in-network cloudlets, and the low cost of storage devices, we study caching in CCN from an economical point of view, where the content providers pay the Internet Service Providers in exchange for caching their content items. We propose an online caching algorithm for CCN that does not require the exact knowledge of content items' popularities to minimize the total cost paid by the content providers. The total cost here is the sum of the caching costs and the retrieval costs. Our analysis shows that the proposed algorithm achieves an O(1) competitive ratio when compared to the optimal offline caching scheme that possesses the exact knowledge of content items' popularities. We also show through simulations that the proposed algorithm can cut the cost incurred by widely used caching schemes such as Leave Copy Down (LCD) and Leave Copy Everywhere (LCE) by up to 65%.