At $99 for a fully-fledged Pos-of-Sale system with fully customizable and expandable framework the main focus for SambaPOS seems to be at offering a strong, affordable base product to as many people as possible and letting these people discover and build new solutions using SambaPOS.
You will find A LOT of support available here on the forums, but to get the best answers, be specific about the help you are seeking.
To get started with SambaPOS I suggest you download the .exe and install the Local DB option at the same time.
Then run SambaPOS and start getting to grips with additng products and a menu.
Once you have products and a menu you can then start to look at more specific customizations that you need to your set-up, whether it is service charges, payment surcharges, custom products, refunds etc.. You will find help for all these specifics within the forum.
It's been a hard 6 months of learning for me, but, over time you will understand a lot more about how SambaPOS works.
Think of it more as a framework, rather than a software product. You won't find an option for "enable service charge for food items" or similar. Instead, you need to build such functionality yourself.
You do this mainly using:
- Automation commands
Also, you sometimes use Custom Reports to present information to you and Entity Screens to layout a series of reports and or action commands (buttons).
When @Emre built SambaPOS he included a bunch of events that we can hook in to. For example when a payment is made a Payment Processed event happens. You can create a rule to fire when this event happens and the rule you create can fire an action. This action can then do something in SambaPOS - It could record something against the customer's record, or it could do something simple like creating a pop-up message to remind the operator about something.
These automation functions are all explained better by others elsewhere, but start with an easier tutorial such as allowing a miscellaneous product at a custom price and you will start to see how these things work.