Someone

function getTotal()
{
  var total = 0.00;

  if (today > endMay)
  {
    total = 25.00;

    if (tshirt.checked)
    {
      total += 15.00;
    }
  }
  else
  {
    if (country.value == 'UK')
    {
      total = 15.00;

      if (osmfmember.value == 'N')
      {
        total += 5.00;
      }
    }

    if (tshirt.checked)
    {
      total += 10.00;
    }
  }
  
  if (osmfmember.value == 'J')
  {
    total += 15.00;
  }

  totalbox.value = total;
  return true;
}