Small difference in LW is not critical for LDR. In QRH the LDR figures are given for max LW. Normally you couldn't be landing higher than that. Even for good to medium braking any credit for less LW than that is mere 10mtrs for flaps full and 20mtrs for Flap3. If overweight then penalty is 40mtrs per T for Flap full or 3. So it's really splitting hair. Nothing is achieved by being so accurate for a ton or less.