flex-box最后一行左對齊有什么解決辦法？

https://jsfiddle.net/t5upngoo/6/

<div class="amount-select">
  <div>50元</div>
  <div>100元</div>
  <div>200元</div>
  <div>300元</div>
  <div>500元</div>
  <div>任意金額</div>
</div>

*{
  padding:0;
  margin:0;
  box-sizing:border-box;
}
.amount-select {
  display: flex;
  margin-right: -3%;
  flex-wrap: wrap;
  width: 100%;
}

.amount-select>div {
  width: 20%;
  height: 100px;
  text-align: center;
  color: #13b7f6;
  border: 1px solid #13b7f6;
  margin-right: 3%;
  margin-bottom: 20px;
}

分為兩個row，上面一行justifyContent設為center，下面一行設為flex-start。下面一行需設置marginLeft