postcss.config.js

const autoprefixer = require('autoprefixer')
const mqpacker = require('css-mqpacker')
const postcss = require('postcss')

// Define the plugin.
const precision = postcss.plugin('postcss-precision', function () {
  const getMatch = (value) => {
    const longTest = /(\d+?\.\d{3,})(%|em|px)/gi

    value = value + ''
    const matches = longTest.exec(value + '')

    if (!matches) return null
    else return matches[1]
  }

  return function (style) {
    style.walkDecls(function (decl) {
      if (decl.value) {
        // Grab array of matches.
        const value = getMatch(decl.value)

        if (!value) return

        // Round two decimal places.
        const rounded = Math.round(parseFloat(value) * 100) / 100

        // Change the value in the tree.
        decl.value = decl.value.replace(value, rounded.toString())
      }
    })
  }
})

module.exports = (ctx) => ({
  plugins: [
    autoprefixer({
      browsers: ['ie >= 11', 'safari >= 9', 'last 2 versions', '> 1%']
    }),
    mqpacker(),
    precision()
  ]
})