Lets assume following scenario: I have Github Actions workflow in my private repository which runs two parallel jobs, each of them takes 5 minute to complete, so workflow itself finishes in 5 minutes.
Do I pay for 5 minutes (that's how long my workflow was running)? Or do I pay for 10 minutes (that's sum of my parallel jobs execution time)?
You would pay for 10 minutes because you used 10 minutes of machine time. The pricing is different by OS so you would also need to take that into account.
How are the minutes calculated? The pricing details at the bottom of https://github.com/features/actions are missing some detail. If my job runs for 1 second, does it get billed as 1 minute?