OpenCart provides analytics, but it is implemented in such a basic form that it is not enough even for a small store.
However, for many questions, you can find a solution using this module IMReport - Advanced reporting of sales and orders (Report “Top Products”, “Customer Group”, “Orders by region (delivery)”, “Manufacturers (volume of products)” and etc).
IMReport (OC 3) - Расширенная отчетность продаж и заказов
IMReport (OC 3) - Расширенная отчетность продаж и заказов предоставляет гибкий инструмент для проведения разностороннего анализа продаж ваших товаров на сайте. Теперь и поддержка закупочной цены (себестоимость)
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IMPORTANT! The IMReport module displays the purchase price (cost) and income (calculated field) only if the corresponding version of the IMStock module is available.