quantopian/zipline — pull request #141 by sender (2013-04-23 03:31:17+00:00)
Title: ENH: add minimum total commission per order to per share commissions

Brokers often use a minimum commission per order, for example see the [flat rate commissions](https://www.interactivebrokers.com/en/index.php?f=commission&p=stocks2#america) from Interactive Brokers. This pull request adds a minimum commission per order to the PerShare commissions class.