How to grep rows that have certain value in a specific column

I have a file as the following

  200.000    1.353    0.086
  200.250    1.417    0.000
  200.500    1.359    0.091
  200.750    1.423    0.000
  201.000    1.365    0.093
  201.250    1.427    0.000
  201.500    1.373    0.093
  201.750    1.432    0.000
  202.000    1.383    0.091
  202.250    1.435    0.000
  202.500    1.392    0.087
  202.750    1.436    0.000
  203.000    1.402    0.081
  203.250    1.437    0.001
  203.500    1.412    0.073
  204.000    1.423    0.065
  204.500    1.432    0.055
  205.000    1.441    0.045  

I would like to grep only the rows that have in the first column the decimal .000 and .500 only so the output would be like this

  200.000    1.353    0.086
  200.500    1.359    0.091
  201.000    1.365    0.093
  201.500    1.373    0.093
  202.000    1.383    0.091
  202.500    1.392    0.087
  203.000    1.402    0.081
  203.500    1.412    0.073
  204.000    1.423    0.065
  204.500    1.432    0.055
  205.000    1.441    0.045