Is there a program to track my home's data usage?

I’m interested in how data in GB we use in a month. I looked the settings in my router but dont see anything like a counter that can be reset each month.

Is there any other simple way to do this? (3 computers on a wireless network as well as a ROKU box we use for netflix etc).

It would have to be done by the router. What model do you have?

Yes, if your router supports sending to a syslog there are numerous programs that will do the analysis. If it doesn’t there may be programs that can do log analysis on your specific router.
If you’re really lucky, your ISP should have a page somewhere that will just tell you what you’re using.

2wire 3800HGV-B

When i connected to it to set my password, I looked through the settings, but didn’t see anything that appeared to track data. Of course, the setting may just have a non-obvious name.

Yeah, my ISP provides a data usage page in my account. I log in and can see my recorded usage on a per-day or a per-month basis.

I can also track usage through my router. I have a LinkSys WRT54-G with Tomato firmware installed, and it tracks usage nicely. As far as i can tell, though, the OP’s 2Wire router doesn’t work with third-party firmware like Tomato or DD-WRT.

Are you also using VOIP or IPTV? You could put your PCs behind a second router with usage monitoring, but it’s easiest to just check here.