Clock Triggering Mechanism via PHP MySQL or >

OK this is likely going to seem a bit out there as I do SEO not PHP but let me see if I can explain what I want to be able to do and perhaps someone can be kind enough to tell me if PHP is the answer.

OK let’s say I want to charge by the minute for a service.

Now let me give an example of what I want to be able to do.

I want a trigger set up thing that will enable me to track time spent on a job which adds the amount to get paid.

So let’s say I was working on three websites all at the same time in a four and half hour time span or thereabouts.

Each site would be different so would need more or less time. It would be very handy to have a switch to turn each job on and off from the clock if you get my meaning?

What I mean is let’s say 3 websites are being designed in a four and half hour period. Each site as I said is different dependent upon time and input. This time and input affecting the pricing. So as one would wait for a reply from one site owners email for content one would want to work on another site. Hence the switches/triggers needed.

Is there something like this PHP out there? I am sure there must be but what would it be called or better still is there an open source thing anything like this that could be adapted to do such things?|

It would also be nice if one could set an amount for each minutes labour time so as work is done and the switches are triggered it tots up the price for the labour part of the job.

Does any of the above sound like something PHP would do? Or would another way to do things be better?

Something like this (granted this isn’t a PHP application, it is a Windows application)?