Economics typically assumes that firms use a model of the environment to choose optimal actions. I use a reform that restricted the set of admissible prices to test this assumption. Specifically, a reform in Israel limited prices to end with X0 as the cents digits (e.g. 2.90 but not 2.99). When consumers are left-digit biased, demand drops at round numbers, hence optimal pricing prescribes bunching at just-below prices and avoiding round prices. Israeli supermarket chains respond to left-digit bias in the long-run and act as if they know this demand structure, setting just-below prices for 45% of prices. This response is consistent with awareness of the bias; However, it implies underestimation of its magnitude since estimated demand should lead to even higher shares of 99-endings. Further, following the reform, 20% of prices were round (e.g. 3.00). If firms were model-based their response to the reform would have been to update immediately according to their beliefs and avoid round prices; However, firms set clearly dominated prices for almost a year, re-learning something they seemed to know. Further, price changes at the product-store level were that 00-endings changed into 90-endings but 90-endings were absorbing. Together these findings suggest that firms learn in a model-free way, which may lead them to be model-free decision makers. Model-free incomplete learning can explain how firms behave sub-optimally in a persistent way and challenges counterfactual exercises that rely on the assumption of model-based optimization.