Can you please take a look at This Demo and let me know How I can add step to code to increment the value every time by adding 10 to the existing until getting to 100? and decrements the value until zero?

As I said i need to have a step on 10 number.

1. <div class="btn-group input-group">
2.     <button type="button" class="btn btn-default minus">-</button>
3.     <button type="button" class="btn btn-default opacity">% 0&nbsp;&nbsp;</button>
4.     <button type="button" class="btn btn-default plus">+</button>
5. </div>
6. 
   
7. $(document).ready(function () {
8. 
   
9.     var i=1;
10.     $(".plus").on("click", function () {
11.         if(i<11) $(".opacity").html("% " +i++);
12.     });
13.     $(".minus").on("click", function () {
14.         if(i>0) $(".opacity").html("% " +i--);
15.     });
16. });