For example, a function that calculates sales tax. The domain is usually positive numbers with at most two decimal places of precision, although for getting gas (at least here in the United States) an extra decimal place of precision is usually added, as maybe in other cases too. The range can actually be any set, as long as it contains all the values that the function can output. So we can let the range be the set of all real numbers, or the set of all complex numbers, or the set of all rationals, or (most restrictively) the set of nonnegative numbers with at most two decimal places of precision.
I suppose one could argue that 0 is also a valid input for the function, returning 0. It's up to preference, I'd say.