This study investigates whether firms round up their operating cash flows and whether this behavior is more prevalent in firms listed in the OTC market compared to those listed in the three major US stock exchanges. Using Benford's law, we find that firms listed in the three major stock exchanges round up earnings but not operating cash flows. However, firms listed in the OTC market round up both earnings and operating cash flows. We also discover that loss firms are more likely to round up operating cash flows than profit firms. Our results support the prediction that firms in the OTC market are more likely to round up operating cash flows than those in the three major stock exchanges. Our study is crucial as it reveals the potential for firms to manipulate accounting numbers by rounding up operating cash flows and provides the first empirical evidence of this phenomenon. This manipulation of operating cash flows could impact the valuation of equity securities for investors and financial analysts using cash flow-based valuation models.