Ixixly, how do you get 10min short of a destination and only then find out you are short of fuel? What have you been doing about fuel management for the rest of the flight? if fuel management and planning is such a challenge, what happens if as Wiz asked it's only 15min or 20min into the reserve?
final reserve is exactly as it says on the tin .it's your final reserve and should not be touched unless something extraordinary happens . It's not contingency fuel which can be burnt for weather deviation, stronger winds etc. If your aeroplane hasn't got the legs for the trip, plan a stop enroute or find an aeroplane that can make it .
Knowing to the litre how much fuel you have (as mentioned by someone earlier) means your decision to stop should be made earlier rather than deliberately continue and land below your final reserve fuel .