Shipping Costs I Cover for a 501(c)(3). Where to deduct?

One of my customers is a 501(c)(3) animal rescue. They purchase, at regular price, stuffed animals I sew from my small business (I am self-employed).  I cover their shipping to help defray costs to the rescue. Can I write off the shipping charges ($250) as a charitable contribution? Or do I just deduct as a business expense on my Schedule C? Or?

Thank you.