JSFiddle - React, Tailwind, and code Playground

HTML

<div id="public">
                          <div class="row">
                              <div class="col-xs-7 col-md-7">
                                  <div class="form-group">
                                      <label for="city">CITY</label>
                                      <input type="text" size="20" autocomplete="off" class="city input-small form-control" placeholder="CITY"/>
                                  </div>
                              </div>
                              <div class="col-xs-4 col-md-4">
                                  <div class="form-group">
                                      <label for="state">STATE</label>
                                      <select class="form-control" id="state" onChange="taxRate()">
                                          <option value="">N/A</option>
                                          <option value="AK">Alaska</option>
                                          <option value="AL">Alabama</option>
                                          <option value="NH">New Hampshire</option>
                                          <option value="NJ">New Jersey</option>
                                          <option value="NM">New Mexico</option>  
                                        </select>
                                        <input type="hidden" id="tax_percent" name="tax_percent">
                                  </div>
                              </div>
                          </div>
                          <div class="row">
                              <div class="col-xs-5 col-md-5">
                                  <div class="form-group">
                                      <label for="zipCode">ZIP CODE</label>
                                      <input id="zip" type="text" size="6" autocomplete="off" class="zipcode form-control" placeholder="ZIP CODE"/>
                                  </div>
                              </div>
                         ...

JavaScript

function taxRate() {
    var tax_rate = .07;
    var order_taxes = 0;
    var tax_percent = 0;
    var subtotal = document.getElementById("order_subtotal").innerHTML;
    subtotal = parseInt(subtotal);
    var total = 0;
    var state = document.getElementById("state").value;
    if (state === 'NJ') {
      order_taxes += +(tax_rate * subtotal).toFixed(2);
      tax_percent = +(tax_rate * 100).toFixed(2);
    }
    
    var el = document.getElementById('order_tax');
    el.textContent = order_taxes;
    
    var total = subtotal + order_taxes;
    var el1 = document.getElementById('order_total');
    el1.textContent = total;
    document.getElementById('tax_percent').value = tax_percent;
}