|You said "minimum 5" or did you mean maximum 5?|
Well, a good router can be used to connect all the PC's and share the internet.
Running an Cyber Caffee does not really need expensive devices eg. servers!
Get good specs of PC's with 10Gigabit Ethernet NICs, a reasonable good router (recommend N Router), and if you go more then 5 PC#s then you would need a switch!
ROUTER <<< >>>> SWITCH <<<< >>>> More then 5 PC's
On top of that, you need an CyberNet Software that control the timing & costs etc.