How to round the total price, display without decimal?
this solved my problem: https://www.drupal.org/project/commerce/issues/3076196
my module:
roundingmodule.info
name: Commerce rounding module.
type: module
description: Rounding.
core: 8.x
package: Custom

roundingmodule.services.yml
services:
  roundingmodule.rounding_order_processor:
    class: Drupal\roundingmodule\RoundingOrderProcessor
    tags:
      - { name: commerce_order.order_processor, priority: -10 }

roundingmodule.commerce_adjustment_types.yml
rounding:
  label: 'Rounding'
  singular_label: 'rounding adjustment'
  plural_label: 'rounding adjustments'
  has_ui: true
  weight: 20

src/RoundingOrderProcessor.php
    &lt;?php

namespace Drupal\roundingmodule;

use Drupal\commerce_order\Adjustment;
use Drupal\commerce_order\Entity\OrderInterface;
use Drupal\commerce_order\OrderProcessorInterface;

/**
 * Processes the order's shipments.
 */
class RoundingOrderProcessor implements OrderProcessorInterface {

  /**
   * {@inheritdoc}
   */
  public function process(OrderInterface $order) {
   
      $rounder = \Drupal::service('commerce_price.rounder');
      $order_total = $order-&gt;getTotalPrice();
      $rounded_total = $rounder-&gt;round($order_total-&gt;divide(100))-&gt;multiply(100);
      $difference = $rounded_total-&gt;subtract($order_total);

      $order-&gt;addAdjustment(new Adjustment([
        'type' =&gt; 'rounding',
        'label' =&gt; 'Rounding',
        'amount' =&gt; $difference,
      ]));
  }

}