<div id="slider">
<figure>
<img src="http://old.maquinadenoticias.com/banner1.jpg" alt="">
<img src="http://old.maquinadenoticias.com/banner2.jpg" alt="">
<img src="http://old.maquinadenoticias.com/banner3.jpg" alt="">
<img src="http://old.maquinadenoticias.com/banner4.jpg" alt="">
<img src="http://old.maquinadenoticias.com/banner5.jpg" alt="">
</figure>
</div>

@keyframes slidy {/*working except slide 5 */
0% { left: 0%; }
20% { left: 0%; }
25% { left: -100%; }
45% { left: -100%; }
50% { left: -200%; }
70% { left: -200%; }
75% { left: -300%; }
95% { left: -300%; }
100% { left: -400%; }
}
@keyframes slidy2 {
0% { left: 0%; }
20% { left: 0%; }
25% { left: -100%; }
40% { left: -100%; }
45% {left: -100%; }
60% { left: -200%; }
65% { left: -200%; }
80% { left: -300%; }
85% { left: -300%; }
/*90% { left: -400%; }*/
100% { left: -400%; }
}

body { margin: 0; } 
div#slider { overflow: hidden; }
div#slider figure img { width: 20%; float: left; }
div#slider figure { 
  position: relative;
  width: 500%;
  margin: 0;
  left: 0;
  text-align: left;
  font-size: 0;
  animation: 10s slidy2 infinite; 
}