If it's Impressive, then you've completed the first skill challenge. That's when the store should waive all fees.
What do you mean by the first skill challenge? If I understand you, there are 3 challenges for the consignment skill: Profits over $25,000 (which my sims exceeded some time back), Sales over 150 items (also exceeded some time ago), and Impressive reputation. For some reason, at the top of the description it says Reputation: Impressive, but at the bottom where the skill challenges are, Impressive reputation is greyed out, which seems rather contradictory. This is my first experience with all this, so it really doesn't make sense to me. But I know that the most recent commission was 1.5%.