I am looking for a POS system which can do the following:

1. Record sales being Customer specific i.e i can attach a customer with a POS sale.
2. POS can record Credit Sale, again being Customer specific.

3. Maintains a record of sales made to a customer and the record gives details of the ITEMS sold too.

4. Can record a sale of item that is entered into POS as a non-standard unit in quantity e.g 0.76 Kg instead of a standard Kg.

I have surfed the internet and found out that their is an enhanced POS module available which can record sales by attaching customer to it but i am not sure if it can serve the rest of the requirements and also i can't download it because i am new in this open source stuff and can't get around using repositories.

So a lot of help along with patience is needed here.