Here is not a API, but much more flexible approach for getting tax rate that I had to use once:
// SETTING DEFAULT VALUES FOR CALCULATION EXAMPLE
/** @var \Magento\Framework\App\Config\ScopeConfigInterface $config */
$countryCode = $config->getValue(\Magento\Shipping\Model\Config::XML_PATH_ORIGIN_COUNTRY_ID);
$customerTaxClassId = $config->getValue('tax/classes/default_customer_tax_class');
/** @var \Magento\Catalog\Model\Product $product */
$productTaxClassId = $product->getData('tax_class_id');
// THE ACTUAL CALCULATION CALL
/** @var \Magento\Tax\Model\Calculation $taxCalculation */
$rate = $taxCalculation->getRate(
new \Magento\Framework\DataObject(
[
'country_id' => $countryCode,
'customer_class_id' => $customerTaxClassId,
'product_class_id' => $productTaxClassId
]
)
);