JSFiddle - React, Tailwind, and code Playground

HTML

<table class="itemTable" cellspacing="0" rules="all" border="1" id="OrdersDataGrid" style="border-collapse:collapse;margin-right:10px;">
	<tbody><tr style="background-color:#E8E8E8;">
		<td class="itemTableHeader itemTableHeader-Id">Pedido</td><td class="itemTableHeader itemTableHeader-Date">Criado</td><td class="itemTableHeader itemTableHeader-Items">Itens</td><td class="itemTableHeader itemTableHeader-Proof">Prova</td><td class="itemTableHeader itemTableHeader-Price">Preço total</td><td class="itemTableHeader itemTableHeader-Status">Status</td><td class="itemTableHeader itemTableHeader-Options">Opções</td>
	</tr><tr class="48 G-CDC2B78C">
		<td class="itemTable       itemTable-Id">G‑CDC2B78C</td><td class="itemTable       itemTable-Date">23/03/2018 12:00</td><td class="itemTable       itemTable-Items"><p class="itemTableLabelWithIcon"><img align="absmiddle" width="18px" height="18px" src="Images/space.gif"> 001 – CARTÃO DE VISITA BIORITMO</p></td><td class="itemTable       itemTable-Proof"><p class="proofLinks"><img align="absmiddle" width="18px" height="18px" src="Images/space.gif"> </p></td><td class="itemTable       itemTable-Price">R$ 35,50</td><td class="itemTable       itemTable-Status"><img align="absmiddle" src="Images/OrderInProcessStatusIcon.png">&nbsp;Em processo</td><td class="itemTable       itemTable-Options">
                     <a id="OrdersDataGrid_ctl03_Linkbutton3" class="siteLink" name="Linkbutton1" href="javascript:__doPostBack('OrdersDataGrid$ctl03$Linkbutton3','')">Detalhes</a>
                 </td>
	</tr><tr class="46 G-CDB4B78C">
		<td class="itemTable       itemTable-Id">G‑CDB4B78C</td><td class="itemTable       itemTable-Date">23/03/2018 11:56</td><td class="itemTable       itemTable-Items"><p class="itemTableLabelWithIcon"><img align="absmiddle" width="18px" height="18px" src="Images/space.gif"> 001 – CARTÃO DE VISITA BIORITMO</p></td><td class="itemTable       itemTable-Proof"><p class="proofLinks"><img align="absmiddle"...

JavaScript

function sumQuantity() {
  
  var elements = document.getElementsByClassName('itemTable-Price');
  var sum = 0;

   for (i=0;i< elements.length;i++) {
      sum += parseFloat(elements[i].innerHTML.replace(/,/,'.').replace('R$',''));
     };
    
   alert(sum);
    
   
}

sumQuantity();