Cumulative internet data transfer {up AND down}

[Richard Owlett <rowlett@cloud85.net>]

I'm interested in investigating cumulative data to/from the internet for 
selected interval ranging from an hour to a week.
My only connection is a device connected thru a USB port.
My web search turned up only discussion of measuring throughput RATE.
Suggestion of keyword(s) for search?
Suggested software?
TIA