If your hours + declared tips were less than minimum wage then they had to pay you minimum wage. That only happened at one large chain I worked at but not at the local, one-off places. Tips were large enough on weekends that it didn't matter much, or at least not enough to risk your job complaining.

The locally run bars I worked at didn't care about tip ratios, but the corporate chains expected you to average 18% tips and would penalize you if you were pulling less than 13% for several weeks -- cuz it either meant you were absolutely terrible at your job, or else you were lying.