def lookup
      request_params = {
        'customerID' => customer_id,
        'cartID' => cart_id,
        'cartItems' => { 'CartItem' => cart_items.map(&:to_hash) },
        'origin' => origin.to_hash,
        'destination' => destination.to_hash
      }

      response = TaxCloud.client.request :lookup, request_params
      TaxCloud::Responses::Lookup.parse response
    end
def lookup
      request_params = {
        'customerID' => customer_id,
        'cartID' => cart_id,
        'cartItems' => { 'CartItem' => cart_items.map(&:to_hash) },
        'origin' => origin.to_hash,
        'destination' => destination.to_hash
      }

      response = TaxCloud.client.request :lookup, request_params
      TaxCloud::Responses::Lookup.parse response
    end
Create a new transaction.
 === Parameters
 [params] Transaction params.
 Lookup the tax rate for the transaction.
 The returned information is based on the originating address, destination address, and cart items.