Short answer is no.
If your Roku devices are RF (Radio Frequency), an IR (Infrared) remote can't communicate with them. The Roku 2 XD is the only infrared device, but Cox remotes are low-end universal remotes by today's standards. Meaning, the codes it will except are for TV sets, DVD and VCR players and audio equipment. I didn't find any streaming devices.
If you want universal control of your devices, you need a high-end universal remote, such as the Logitech 900 or 1100. Look for universal remotes with multiple protocols, such as IR, RF, Bluetooth, Wifi, etc. These remotes connect to the manufacturers websites, you select your A/V devices and then it downloads all codes. The databases are updated all the time so if a Roku 4 is released...your high-end universal remote can download its codes.