Yes, you are up against base 2 limitations. It is the same as in base 10, you cannot represent $\frac 13=0.\overline 3$ exactly because it has a prime factor that does not divide $10$. $0.1_{10}=0.00011\overline{0011}_2$. It is a repeating "decimal" because of the factor $5$ in the denominator. Why are you using quotToFloat? It looks like your package has exact rationals, so you can just subtract them and check whether the difference is zero for equality.