Amazon CloudFront: How to get monthly cost breakdown per distribution?

I'd like to manage the hosting for multiple clients, using my own Amazon CloudFront account. Each client has its own CloudFront distribution. But the AWS monthly bill doesn't break down by distribution. How can I find out what the cost was for each distribution?

Ideally, the solution will also work for S3. With S3, I can use "cost allocation tags" for this purpose I believe, but those don't seem to apply to CloudFront. Is there a single solution or best practice I can use that will work with both, to learn the cost incurred for a client across CloudFront and S3?

If the only solution is to create a separate AWS account per client, what's the best practice for doing that? Since I'm paying all the bills on behalf of these multiple clients, I'd like to keep the accounting and account management simple on my side.