JSFiddle - React, Tailwind, and code Playground

HTML

<div class="goods">
    <div class="name">Название товара 1</div>
    <div class="goods-count">
        <span class="amount">
            <input type="button" class="down" value="-" data-id="1">
            <input type="text" class="counter" value="1" size="4" data-price="5000" data-count="1" data-id="1"> шт
            <input type="button" class="up" value="+" data-id="1">
        </span>
    </div>
    <div class="goods-price"><span class="sum" data-id="1">5000</span> руб.</div>
</div>

<div class="goods">
    <div class="name">Название товара 2</div>
    <div class="goods-count">
        <span class="amount">
            <input type="button" class="down" value="-" data-id="2">
            <input type="text" class="counter" value="1" size="4" data-price="1000" data-count="1" data-id="2"> шт
            <input type="button" class="up" value="+" data-id="2">
        </span>
    </div>
    <div class="goods-price"><span class="sum" data-id="2">1000</span> руб.</div>
</div>

<div class="goods">
    <div class="name">Название товара 3</div>
    <div class="goods-count">
        <span class="amount">
            <input type="button" class="down" value="-" data-id="3">
            <input type="text" class="counter" value="1" size="4" data-price="3000" data-count="1" data-id="3"> шт
            <input type="button" class="up" value="+" data-id="3">
        </span>
    </div>
    <div class="goods-price"><span class="sum" data-id="3">3000</span> руб.</div>
</div>

<div>Итого: <span id='total'>9000</span> руб.</div>

JavaScript

$(document).ready(function() {
  var updateTotalPrice = function() {
    var totalPrice = 0;
    $('.sum').each(function(index, elem) {
      totalPrice += parseInt($(elem).html());
    });
    $('#total').html(totalPrice);
  }
  var increment = function(elem, plus) {
    var id = elem.getAttribute('data-id');
    if (id == null) throw new Error('This element has no data-id attribute');
    var currentCount = parseInt($('.counter[data-id="' + id +  '"]').val());
    var newCount = currentCount + plus;
    var unitPrice = parseInt($('.counter[data-id="' + id +  '"]').attr('data-price'));
    var totalPrice = newCount * unitPrice;
    $('.counter[data-id="' + id +  '"]').val(newCount);
    $('.sum[data-id="' + id +  '"]').html(totalPrice);
    updateTotalPrice();
  };
  $('.up').on('click', function() {
    increment(this, 1);
  });
  $('.down').on('click', function() {
    increment(this, -1);
  });
});