I don't know about total, but ifconfig can tell you the amount of traffic going over a network interface since it was connected. For example, my wireless card:
That was a little web surfing. Blue is received, red is sent. Just go to a terminal and type: when you're connected and look at those two fields.
wlan0_ren Link encap:Ethernet HWaddr 00:1B:77:9C:BC:F9
inet addr:192.168.97.19 Bcast:192.168.97.255 Mask:255.255.255.0
inet6 addr: fe80::21b:77ff:fe9c:bcf9/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:7532 errors:0 dropped:0 overruns:0 frame:0
TX packets:2767 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:3010523 (2.8 MB) TX bytes:644700 (629.5 KB)
Hope this helps.