@Toshack ,
Square is a little different to traditional banks, you generally buy the hardware outright, so the fees are literally the transaction costs, and any additional features you subscribe to. Without knowing the specifics of your business its hard to say whether you'd need any subscription features, but the Square for restaurants, and Square for retail free offerings are quite generous.
Retail comparison:
https://squareup.com/help/au/en/article/5980-compare-square-for-retail-and-square-point-of-sale
Restaurants comparison:
https://squareup.com/help/au/en/article/6525-compare-square-for-restaurants-and-square-point-of-sale
The processing fees are slightly lower when using square register or square terminal
