Automatic discount for all registered users

Create a group for registered users, for example 10%
Look at her id in the browser address bar

Next, open the file view/RegisterView.php and we are looking for

elseif($user_id = $this->users->add_user(array('name'=>$name, 'email'=>$email, 'password'=>$password, 'enabled'=>$default_status, 'last_ip'=>$_SERVER['REMOTE_ADDR'])))

Adding 'group_id' => [group ID] to the array
After 'name'=>$name, add 'group_id' => 2,
For example, it looks like this

elseif($user_id = $this->users->add_user(array('name'=>$name, 'group_id' => 2, 'email'=>$email, 'password'=>$password, 'enabled'=>$default_status, 'last_ip'=>$_SERVER['REMOTE_ADDR'])))

And now, when registering, the user will automatically receive the discount you set.