Anima: Beyond Fantasy has a rule for situations where a fight would need to go on for a very long time for dramatic purposes. It's designed for insanely skilled fighters that have epicly long battles, but the adaptation is easy enough.

Regular rounds are 3 seconds each, which is pretty equivalent to Exalted.
From there the length of rounds doubles each round until each is a full minute long.
Round 1 - 3 Seconds
Round 2 - 6 Seconds
Round 3 - 12 Seconds
Round 4 - 24 Seconds
Round 5 - 1 Minute

Anima stops at full minute length rounds,...