Scroll steps

Here’s my code:

 <ion-scroll direction="y">
   <div class="list" ng-init="items=[8,9,10,11,12,13,14,15,16,17,18]">
        <label class="item item-radio" ng-repeat="item in items">
              <input type="radio" name="group">
              <div class="item-content">
               {{item}}
              </div>
        </label>
   </div>
 </ion-scroll>

How can I ask ion-scroll to only scroll to 50px’s multiples in order to never “break” an item ?