Compute time of Azure is changed by the hour, but notice the fine print:

• Deploy at 10:50 and delete at 11:10 will be charged as two hourd.
• Again deploy at 11:40 and 12:10 delete will add another two hours to the bill, because the second deploy goes to ‘another’ instance/server which is registered two hours for you too.
• Two webroles in a service means two hours.

Eventually I had to pay 25 hour compute within 8 hours of work.