Jstl

<c:forEach var="item" items="${sessionScope.carrinho}">

  <c:set var="varPreco" value="${item.preco}" scope="page"/>

  ${item.descricao} - R$ ${item.preco}

  <c:set var="precoTot" value="${item.preco + $[varPreco]}" scope="page"/>

</c:forEach>

Total: <c:out value=${precoTot}>