One lot purchase requires 100.000 base currency units. If talking about the USD/JPY minimum order, with standard 1:100 leverage you need $1,000 for purchase. If the broker requires an order’s amount of less than $1,000, this means that the order won’t be placed in the market. Of course, the broker can collect his clients’ orders, summing them up, and bringing them to the market then. But usually this does not happen. Orders are made on the broker’s servers. In this case, clients trade against each other, actually. One’s profit is other’s loss. Such brokers are called dealing centers. You can make some money there, but not a lot. Draw conclusions.