This study examined the relationship between stock control practices and the management of costs in organisations, using the Mukwano Group of Companies as the case. A quantitative design was adopted, and a coded dataset of 80 stores and warehouses was analysed using descriptive statistics, Pearson correlations, multiple linear regression of inventory-related costs as a percentage of sales and binary logistic regression of whether a cost-reduction target was met, supported by diagnostic tests. The study results indicated that inventory-related costs averaged 6.2% of sales, and that ABC classification (B = -1.74 percentage points, p < 0.001), more frequent stock counts, integrated inventory software, reorder-point rules, staff training and more reliable suppliers significantly reduced costs, while a larger number of items and a higher share of perishable stock increased them. The logistic model of target achievement was not statistically significant overall, which was attributed to the small number of unsuccessful stores. The diagnostic tests were satisfactory. The study concluded that systematic stock control practices were associated with lower inventory costs, and it recommended ABC classification, regular counts, inventory systems, supplier management and staff training.