++ - stated price not including GST (VAT) and Service Charge (1st plus is for GST, 2nd for Service Charge). It's so commonplace, that even places without Service Charge use "++" even if it's only GST.

GST is 8%, Service Charge 10%, nett price is the price with both GST and Service Charge included.

Other than copying Americans, I could never fathom why they chose to display gross prices with "++" symbol - except the obvious, the price looks "lower" if you don't add "++" amounts to it.