Dollar Tree Inc. (Nasdaq: DLTR US) shares climbed the most in more than two decades after the company boosted its share-repurchase authorization and said it would move above the $1-an-item price point that gave the discounter its name. The board lifted potential buybacks by $1.05 billion to $2.5 billion, the company said in a statement Wednesday. Separately, Dollar Tree unveiled a plan at its legacy stores to begin testing sales of products that cost more than $1.