You did the math right, but the cache line tag logic and coupled CAM are negligible. Sure, they may add a few million or so, but not anywhere near 5% of 100M.
Umm, "a few million" is around 4 to 5 million...which can equate to "about 5% of 100 million"...so yeah, I take that to mean somewhere near and potentially exceeding 5% of 100 million. Just to be anally retentive.
The only perfect science is hind-sight.