Convert a percent rating to a five star grade

gistfile1.txt

   0 .....  
   1 .....  21 X....  41 XX...  61 XXX..  81 XXXX.
   2 .....  22 X....  42 XX...  62 XXX..  82 XXXX.
   3 .....  23 X....  43 XX...  63 XXX..  83 XXXX.
   4 .....  24 X....  44 XX...  64 XXX..  84 XXXX.
   5 /....  25 X/...  45 XX/..  65 XXX/.  85 XXXX/
   6 /....  26 X/...  46 XX/..  66 XXX/.  86 XXXX/
   7 /....  27 X/...  47 XX/..  67 XXX/.  87 XXXX/
   8 /....  28 X/...  48 XX/..  68 XXX/.  88 XXXX/
   9 /....  29 X/...  49 XX/..  69 XXX/.  89 XXXX/
  10 /....  30 X/...  50 XX/..  70 XXX/.  90 XXXX/
  11 /....  31 X/...  51 XX/..  71 XXX/.  91 XXXX/
  12 /....  32 X/...  52 XX/..  72 XXX/.  92 XXXX/
  13 /....  33 X/...  53 XX/..  73 XXX/.  93 XXXX/
  14 /....  34 X/...  54 XX/..  74 XXX/.  94 XXXX/
  15 X....  35 XX...  55 XXX..  75 XXXX.  95 XXXXX
  16 X....  36 XX...  56 XXX..  76 XXXX.  96 XXXXX
  17 X....  37 XX...  57 XXX..  77 XXXX.  97 XXXXX
  18 X....  38 XX...  58 XXX..  78 XXXX.  98 XXXXX
  19 X....  39 XX...  59 XXX..  79 XXXX.  99 XXXXX
  20 X....  40 XX...  60 XXX..  80 XXXX. 100 XXXXX

percent_to_stars.php

<?php 

function percent_to_stars($p, $star, $half, $empty)
{
  $stars   = floor((round($p / 10) / 2));
  $halves  = round($p / 10) % 2;
  $empties = 5 - $stars - $halves;
  return str_repeat($star, $stars)
       . str_repeat($half, $halves)
       . str_repeat($empty, $empties);
}

for ($i=0; $i < 100; $i++)
{
  print str_pad($i, 2) . " "; 
  print percentToStars($i, "X", "/", ".");
  print "\n";
}