This example shows a bar chart of total retail sales aggregated by product category, highlighting the top 15 categories by revenue. It loads a CSV dataset and uses `d3.rollups` to group and sum the “Total Amount” field for each category. The visualization is rendered as an SVG using D3 v7, with a band scale for category positioning, a linear scale for sales values, gridlines, value labels on each bar, and rotated axis tick labels for readability.