Each submission is billed according the Billing Resolution (e.g. 1 minute) and the Minimum Billable Duration (e.g. 5 minutes) for your account. To see what it is, just mouseover Account Type in the upper right of any page after you've logged in.
Durations of all submissions on the CaptionSync system are stored to the minute with second round up to the next minute. For example, 10 seconds of audio will show with a duration of 1 minute, 80 seconds of audio will show with a duration of 2 minute, etc.
With the above resolution and minimum example if you did a submission which is 3:45 (3 minutes and 45 seconds), since this is less than the 5 minute minimum, you would be billed 5 minutes. On the Status of Submissions page for this one, you would see a Duration of 4 minutes and a Billable Duration of 5 minutes.
With the same resolution and minimum if you did a submission which is 6:05 (6 minutes and 5 seconds), you would be billed 7 minutes. On the Status of Submissions page for this one, you would see a Duration of 7 minutes and a Billable Duration of 7 minutes.
For a list of all billable submissions, go to Billing -> Billable Submissions. By default, only submissions made within the Last 30 Days are displayed; you can change the value for Date to view older submissions. You can query for the submissions using multiple other filters, like Status, Batch ID, Source, Submission Type, Language, Description, Media File and Result Review. You can see these other filters by expanding More options. Then click Submit Query:
Note that the Billable Duration for historical submissions are calculated based upon the Billing Resolution and Minimum Billable Duration in affect at time of submission (which may be different than it is today).