Belgium uses the Euro as currency, and typically you will find that prices in the country are similar to those in major cities in the UK. Tipping is not compulsory, although for good service it is expected and 10-15% will suffice. Many restaurants already include a service charge on meals, meaning that you do not need to leave any additional money.
Goods on display in shops already include sales taxes such as VAT, so the price that you see on the ticket is the price that you will pay at the checkout.