Guest tabs

So everything everyone buys here in the hostel goes on a tab and they pay it off at the end of their stay - I'm sure some of you are wondering how many people run off without paying and the answer is sweet bugger all. So given that it seems to be working, I'd like to keep it. It creates quite an open, honest atmosphere and means neither I nor the guests have to fiddle around with change for every purchase. There are also 'creative accounting' benefits but thats beside the point.

Currently I'm writing everything down on a guest list and then transferring it onto a spreadsheet at the end of the day. This is, without putting too fine a point on it, the bane of my existence at the moment. I've got 4 or 5 days worth of tabs to update (which is fine, as the average length of stay here is nearly about a week) and it's... well, its not fun.

For next season I'm hoping (HOPING) to be able to use a web-based PMS on a tablet and effectively eliminate the need for a reception desk at all but I'm yet to find a suitable PMS with a 'cash register' feature thats easy to use and doesnt require clicking on 3 or 4 different buttons just to bring up the 'sales' option.

I remember when I was travelling central america, a LOT of hostels operated tab systems - most of which as far as I could tell were simple paper based which as far as I can tell were perfectly accountable but presumably included an awful lot of paper work at the end of the day.

So what's my question? Has anyone had any experience operating tabs for guests and how did you do it? I'm convinced there's an easier way than I'm currently using (which is already easier than the system I inherited) but there must be a way of including a very simple cash register system for each guest inside a PMS. Im pretty handy with spreadsheets and would be more than happy to try my hand at some programming over the winter, so really I was just hoping that someone could point to their own experience or perhaps state the bleeding obvious thats staring me in the face and I'm unable to see!

Yamas!
gordo