scrupulous
Very careful to do what is right and exact.
Scrupulous means being extremely careful to do what is right and correct, paying close attention even to small details. A scrupulous person takes their responsibilities seriously and refuses to cut corners, even when no one is watching.
When a scientist is scrupulous about recording experimental data, she writes down every measurement precisely, double-checks her numbers, and never guesses or rounds off results carelessly. When a store owner is scrupulous about giving correct change, he counts it twice to make sure customers receive exactly what they're owed.
The word suggests moral precision and thoroughness. Someone scrupulous about keeping promises honors every commitment, large or small. A scrupulous student working on a group project does their full share of the work, meets every deadline, and makes sure their contributions are accurate and complete.
Being scrupulous can sometimes feel harder than taking shortcuts, but it builds a reputation for reliability and integrity.