smartcalcs-php-client-demo.php

<?php
require __DIR__ . '/vendor/autoload.php';

$taxjar = TaxJar\Client::withApiKey('YOUR API TOKEN');

$order_taxes = $taxjar->taxForOrder([
  'from_country' => 'US',
  'from_zip' => '07001',
  'from_state' => 'NJ',
  'to_country' => 'US',
  'to_zip' => '07446',
  'to_state' => 'NJ',
  'amount' => 16.50,
  'shipping' => 1.5,
  'line_items' => [
    [
      'quantity' => 1,
      'unit_price' => 15.0,
      'product_tax_code' => 31000
    ]
  ]
]);

echo $order_taxes->amount_to_collect;