Why do tracert latencies not add up to ping latency?

Traceroute involves sending UDP packets to each node along the way, and waiting for its timeout response (then moving on to the next node), whereas a ping is just forwarded. What you're seeing is the time it takes for each node to respond to the request instead of just forwarding a small packet.

This is a pretty nice explanation of the whole process, and the differences.

http://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/ios-software-releases-121-mainline/12778-ping-traceroute.html

Have a look at the performance section, which explains also why ping isn't a particularly accurate method for determining latency.