input: Write a function to improve the efficiency of the provided Python code snippet for determining commission rates based on gross sales. The function should correctly return the appropriate commission rate as a floating point number. If the gross sales are 10000 or more, the commission rate should be 0.1. If the gross sales are between 5000 and 9999, the commission rate should be 0.07. If the gross sales are less than 5000, the commission rate should be 0.05.
  assert determine_commission_rate(11000)==0.1
  assert determine_commission_rate(7500)==0.07
  assert determine_commission_rate(3000)==0.05
  assert determine_commission_rate(5000)==0.07
  assert determine_commission_rate(10000)==0.1
output: def determine_commission_rate(gross_sales):
      if gross_sales >= 10000:
          return 0.1
      elif gross_sales >= 5000:
          return 0.07
      else:
          return 0.05