What's the total come to, including insurance and tax?
Literal
Insurance, tax [obj-を] include-and, total amount [topic-は] how much becomes (polite)?
含めて ('including') is the て-form of 含める ('include'), functioning as a prepositional-like 'including X.' The pattern [list]を含めて ('including [list]') is standard for 'including X and Y.' 合計金額 ('total amount') + ~になる ('comes to') is the conventional way to ask for a sum.