We have been discussing billing increments in another thread and I have discovered that my carry over from the corporate world is a novel approach to most in the VA world.
Working in legal and accounting (blah!) I had to do a time sheet every day, even as a PA (double blah!). These were kept in increments of 6 minutes. Our billilng policy was "every 6 minutes or part thereof", so if a task took 7 minutes, the client was charged 2 units = 12 minutes. Because I did this for so many years, it has now become 'normal' to me and I have been using this for my clients since I started this year. I didn't realise that it was more normal to round up to 15 minutes (doh!). I do find that the clients seem happy when I tell them and one commented that they thought it was reasonable compared to others - at the time I didn't understand why!
I use Time Stamp to record my time (since it is free) and even though you can set increments, it doesn't work well in that respect. If you have lots of interruptions such as phones, kids etc, the system rounds up on EVERY time you stop, not just at the end over the overall time sheet. So I just wait till I've finished the whole task and round up to the nearest multiple of 6 myself and enter that on my invoice.
Therefore, 1 hour = 60 mins = 10 units of 6 mins per hour. So, 45 mins work = .8 because 48 mins is 6 x 8, the next multiple of 6 that fits my time.
I also adjusted my hourly rate after I first started because I realised I needed something that divided easily into 6. I am currently UA$XX ph, so I can easily divide this into 6 or into 4 if the project is one that I might actually tell them I will charge in 15 min increments, such as designing a flyer (although I usually forget and just do the 6 min thing - again - force of habit).
Also - this works well in the invoicing system. I am using the QuickBooks Quickstart (again because it was free) and this way I can enter 1.6 in the units and my rate and it will correctly enter my fee.
I would be interested to see how this compares to others since I'm only a newbie to the whole thing, so would like to make sure I haven't set myself up with a dud system!