Some rhymes in English verse are
a) rhymes to the eye only, e.g. find/wind (the latter in the sense of "moving air");
b) rhymes by convention, e.g. eye/symmetry.
Type B rhymes often date from earlier forms of English, when the terminal sounds did indeed rhyme. (In Middle English, for instance, many words that now end in "-y" ended in "-ye".)
In 19th and early 20th century recitation, such rhymes were often deliberately mispronounced, to allow the full rhyme. You rarely hear such deliberate mispronunciations nowadays, however: the tendency is to pronounce the words naturally.
Since the last syllable of "symmetry" and "eye" are diphthongs, a faint rhyme may in any case still be detected.
(I should say that to my ears, this kind of rhyme has its own peculiar charm.)