Hopefully faster/better version of previous tax function

gistfile1.js

function tax(total) {
  var accum = 0;

  var tiers = [
    0,
    14000,
    48000,
    70000,
  ]

  if (total <= tiers[1])
    return total*0.1254

  accum += tiers[1]*0.1254
  total -= tiers[1]

  var accumtier2 = tiers[2]-tiers[1]
  if (total <= accumtier2)
    return accum + total*0.1954

  accum += accumtier2*0.1954
  total -= accumtier2
  
  var accumtier3 = tiers[3]-accumtier2
  if (total <= accumtier3)
    return accum + total*0.3204

  accum += accumtier3*0.3204
  total -= accumtier3

  accum += total*0.3504

  return accum
}