You may have better luck with your question at the AWS Developer forum and I think this thread may be helpful to you
Partial quote from thread linked to above.
"EC2 data transfer usage will be given in bytes for each type of Data Transfer (for eaxmple, DataTransfer-Regional-Bytes, DataTransfer-Out-Bytes or DataTransfer-In-Byte).
Regarding inbound data transfers, on December 8, 2009, we announced free inbound data transfers to AWS through June 2010. You can read the article here:
We also post data transfer pricing on the detail page for each Amazon Service. For EC2 data transfer pricing, please review the EC2 pricing details here:
There is no Data Transfer charge between Amazon EC2 and other Amazon Web Services (like S3) within the same region (i.e. between Amazon EC2 US West and Amazon S3 in US West). Data transferred between Amazon EC2 instances located in different Availability Zones in the same Region will be charged Regional Data Transfer. Data transferred between AWS services in different regions will be charged as Internet Data Transfer on both sides of the transfer.
Data transfers between separate AWS Regions, or via public IP addresses will be charged at the normal rate."
Quote from Daryl W on this thread.