Final Price is a simple WooCommerce plugin that shows an additional total price field when the user updates the quantity of the selected product. The plugin only works for simple and variable products.
The total price box is displayed above the “Add to cart” button.
NOTE ON DECIMAL ACCURACY:
For the decimal precision, make sure you set the precision you want under WooCommerce Settings -> Currency Options -> Number of Decimals. The plugin uses this setting to match the current shop options.