Every buck I overshoot might cost me between $0.0187 and $0.025 in tax processing fees, so I am aiming for perfect precision.

(my year-end plan is to get to $15k in spend this year for the free night, and earn four more EQN to reach the next milestone award, another free night. These two goals are reasonably well aligned as far as the remaining spend required, +- $850 or so. And then cancel the card and follow your example of churning earning a new SUB).