The latest data point for COST's Return on Sales (ROS) in Q1'26 stands at 3.89%, reflecting a modest decline from the previous quarter's 4.13% and indicating potential margin pressures amid recent operational dynamics. Over the period from Q3'23 to Q1'26, ROS has exhibited an overall upward trend, rising from 3.37% to a peak of 4.13% in Q3'25, with notable volatility including a dip to 3.77% in Q1'25 before recovering; the area chart highlights steady improvement in profitability efficiency, though the recent softening suggests caution for sustained growth in the near term.