a^2/a^2 not simplified

[Henri.Cohen@math.u-bordeaux1.fr]

At \p 19 (for instance), if I write

res=((5.421010862427522171 E-20 + 0.E-19*I)*a^4 + (5.000000000000000000 + 0.E\
-18*I)*a^2 + (5.421010862427522171 E-20 + 0.E-19*I))/a^2

and then round(res) I obtain

%107 = 5*a^2/a^2

I can understand why, but still this is not very nice. Two questions:
1) Is this a bug or a feature?
2) How can I "simplify" %107, the simplify command does not work.

H. Cohen