A retail checkout system for allowing a plurality of customers to checkout one or more product items of at least one set of product items of a given type that has an estimated mean weight and deviation from the estimated mean weight associated with the set of product items, the system comprising: a retail checkout weight scale; and a checkout engine that is operative and configured to determine a mean anticipated cumulative weight and a distribution from the mean anticipated cumulative weight for at least one product item for which a customer initiated the acquisition of respective weight-information; determine a factual cumulative weight of the customer's shopping receptacle placed on the retail checkout weight scale of the retail checkout system; and determine whether the factual cumulative weight meets a checkout criterion with respect to the distribution from the mean anticipated cumulative weight.