Lowest locants are decided at the first point of difference, not by the sum of the locants. What is the IUPAC name of $\mathrm{CH}{}_3-\mathrm{CH}(\mathrm{CH}{}_3)-\mathrm{CH}{}_2-\mathrm{CH}{}_2-\mathrm{CH}{}_2-\mathrm{C}(\mathrm{CH}{}_3){}_2-\mathrm{CH}{}_2-\mathrm{CH}{}_3$?

The longest chain has eight carbons. Numbering from the left gives the locant set {2,6,6} and from the right {3,3,7}. The sums are 14 and 13, but the rule compares the sets term by term at the first point of difference: 2 < 3, so {2,6,6} is lower. The name is 2,6,6-trimethyloctane.