You will have to talk to an engineer at AHRI or Lennox for all the info. Depends on the matchup of the type of evap coil with the condensor. There are A coils and case coils etc. They design the unit to meet the SEER rating for efficiency and to be eligible for any gov't rebates not to get an exact tonnage/btu's. Never have in the last 50 yrs. The compressor may not be exactly 5 tons as they technically rate them in horsepower. Gets to be a VERY in depth conversation that only engineers understand. You never get the exact Btus as the amount of freon in the lineset varies with the length of it and how close to prefect the installer can get the subcooling/approach temp. SEER is what it costs to run irregardless of the Btus/tonnage and that is what I would be concerned with. If a car is rated for 50mpg and its sister is rated for 48mpg you would buy the 50 mpg as it costs less to run. Ie Ford Escape and Mazda Tribute, almost the same vehicle using interchangeable parts but one may get better mileage.
"Cut it twice and it is still too short".