Comment by xandrius

What I think is happening is that the place is specifically charging different tax rates for each part of the pizza. That does seem odd but the alternative would be to tax the whole of the pizza at a higher tax rate than the one presented. Example, most countries might put a whole pizza at, say, 10% VAT, while here part of it is at, say, 4% and the rest at 10%. Ideally that's cheaper.