BigQuery Billing - difference between JOBS table and Billing report

[sadeveloper]

I have a question about billing - trying to reconcile the billing amount that we see on the report vs the total bytes billed from JOBS.

For the JOBS, the query I am using (assumption is $5 per TB processed): 

select round(sum(total_bytes_billed)/(1024*1024*1024*1024)*5) from region-us.INFORMATION_SCHEMA.JOBS
where creation_time > current_timestamp() - interval 30 DAY;

For the billing report (https://console.cloud.google.com/billing) : I have filtered the report for last 30 days, selected only BigQuery service (not the BI Engine). Also selected only the relevant project. 

The cost as per billing report shows as more than twice the we are getting from JOBS. What could account for the difference?