Edit in JSFiddle

<script src="https://unpkg.com/vue/dist/vue.js"></script>
<script src="https://cdn.rawgit.com/chrisvfritz/5f0a639590d6e648933416f90ba7ae4e/raw/974aa47f8f9c5361c5233bd56be37db8ed765a09/currency-validator.js"></script>

<div id="app">
  <currency-input 
    label="Price" 
    v-model="price"
  ></currency-input>
  <currency-input 
    label="Shipping" 
    v-model="shipping"
  ></currency-input>
  <currency-input 
    label="Handling" 
    v-model="handling"
  ></currency-input>
  <currency-input 
    label="Discount" 
    v-model="discount"
  ></currency-input>
  
  <p>Total: ${{ total }}</p>
</div>
Vue.component('currency-input', {
  template: '\
    <div>\
      <label v-if="label">{{ label }}</label>\
      $\
      <input\
        ref="input"\
        v-bind:value="value"\
        v-on:input="updateValue($event.target.value)"\
        v-on:focus="selectAll"\
        v-on:blur="formatValue"\
      >\
    </div>\
  ',
  props: {
    value: {
      type: Number,
      default: 0
    },
    label: {
      type: String,
      default: ''
    }
  },
  mounted: function () {
    this.formatValue()
  },
  methods: {
    updateValue: function (value) {
      var result = currencyValidator.parse(value, this.value)
      if (result.warning) {
        this.$refs.input.value = result.value
      }
      this.$emit('input', result.value)
    },
    formatValue: function () {
      this.$refs.input.value = currencyValidator.format(this.value)
    },
    selectAll: function (event) {
      // Workaround for Safari bug
      // http://stackoverflow.com/questions/1269722/selecting-text-on-focus-using-jquery-not-working-in-safari-and-chrome
      setTimeout(function () {
      	event.target.select()
      }, 0)
    }
  }
})

new Vue({
  el: '#app',
  data: {
    price: 0,
    shipping: 0,
    handling: 0,
    discount: 0
  },
  computed: {
    total: function () {
      return ((
        this.price * 100 + 
        this.shipping * 100 + 
        this.handling * 100 - 
        this.discount * 100
      ) / 100).toFixed(2)
    }
  }
})