getTotalAmount example

'zipcode' => $customer->getBillingAddress() ? $customer->getBillingAddress()->getZipcode() : '',
            'city' => $customer->getBillingAddress() ? $customer->getBillingAddress()->getCity() : '',
            'phone' => $customer->getBillingAddress() ? $customer->getBillingAddress()->getPhone() : '',
            'additional_address_line1' => $customer->getBillingAddress() ? $customer->getBillingAddress()->getAdditionalAddressLine1() : '',
            'additional_address_line2' => $customer->getBillingAddress() ? $customer->getBillingAddress()->getAdditionalAddressLine2() : '',
            'country_id' => $customer->getBillingAddress() ? $customer->getBillingAddress()->getCountryId() : null,
            'country_name' => $customer->getBillingAddress() ? $customer->getBillingAddress()->getCountry()->getName() : '',
            'state_id' => $customer->getBillingAddress() ? $customer->getBillingAddress()->getStateId() : '',
            'age' => $customer->getAge(),
            'count_orders' => (int) $customer->getOrderInformation()->getOrderCount(),
            'product_avg' => (float) $customer->getOrderInformation()->getAvgProductPrice(),
            'invoice_amount_sum' => (float) $customer->getOrderInformation()->getTotalAmount(),
            'invoice_amount_avg' => (float) $customer->getOrderInformation()->getAvgAmount(),
            'invoice_amount_min' => (float) $customer->getOrderInformation()->getMinAmount(),
            'invoice_amount_max' => (float) $customer->getOrderInformation()->getMaxAmount(),
            'first_order_time' => $this->formatDate($customer->getOrderInformation()->getFirstOrderTime()),
            'last_order_time' => $this->formatDate($customer->getOrderInformation()->getLastOrderTime()),
            'has_canceled_orders' => $customer->getOrderInformation()->hasCanceledOrders(),
            'ordered_at_weekdays' => $this->implodeUnique($customer->getOrderInformation()->getWeekdays()),
            'ordered_in_shops' => $this->implodeUnique($customer->getOrderInformation()->getShops()),
            'ordered_on_devices' => $this->implodeUnique($customer->getOrderInformation()->getDevices()),
            'ordered_with_deliveries' => $this->implodeUnique($customer->getOrderInformation()->getDispatches()),
            'ordered_with_payments' => $this->implodeUnique($customer->getOrderInformation()->getPayments()),