JSFiddle - React, Tailwind, and code Playground

HTML

<form action="">
  <div class="btnGroup">
    <button class="minus">-</button>
    <input type="number" name="N1" value="0" min="0" placeholder="Количество проданных шт">
    <button class="plus">+</button>
  </div>
  <div class="btnGroup">
    <button class="minus">-</button>
    <input type="number" name="N2" value="0" min="0" placeholder="Количество проданных шт">
    <button class="plus">+</button>
  </div>
  <div class="btnGroup">
    <button class="minus">-</button>
    <input type="number" name="test" value="0" min="0" placeholder="Количество проданных шт">
    <button class="plus">+</button>
  </div>
  <div class="btnGroup">
    <button class="minus">-</button>
    <input type="number" name="foo" value="0" min="0" placeholder="Количество проданных шт">
    <button class="plus">+</button>
  </div>
</form>

<div class="result">
  <div id="vsegostuk"></div>
  <div id="vsegoml"></div>
  <div id="summaprod"></div>
</div>

CSS

.btnGroup {
  outline: dashed 1px gray;
  margin: 10px;
  padding: 5px;
}

.result div {
  border: solid 2px lightgray;
}

JavaScript

const price = 10
const volumes = {
	'test': 8,
  'foo': 3.2,
  'N1': 1.5,
	'N2': 3.4,
}


function calculate() {
	const form = this

	let totalVolume = 0
  let totalSum = 0;
  let totalCount = 0

  $('input', this).each(function(){
  	let inputName = this.name
    
    let count = parseFloat(this.value)
    let volume = volumes[inputName] * count
  
  	totalCount += count
  	totalVolume += volume
  	totalSum += volumes[inputName] * price
  })
  
	$('.result #vsegostuk').html(totalCount)
  $('.result #vsegoml').html(`Вы израсходовали всего ${totalVolume}мл.`)
  $('.result #summaprod').html(`Вы сегодня продали товаров на сумму ${totalSum}р."`)
}


function increase(evt) {
	evt.preventDefault()
	let $input = $(this).closest('.btnGroup').find('input')
  $input.val( parseInt($input.val()) + 1)
  $input.change()
}
function decrease(evt) {
	evt.preventDefault()
	let $input = $(this).closest('.btnGroup').find('input')
  $input.val( parseInt($input.val()) - 1)
  $input.change()
}




$('form').on('input change', calculate)
$('form .plus').on('click', increase)
$('form .minus').on('click', decrease)