A "white lie" - a falsehood which does not cause any harm - is not as serious as cheating or being dishonest in business, but it is still prohibited. In limited cases, lying is permitted; for instance where it will bring peace between people. Moses’ brother Aaron is praised for the way he made peace between quarreling parties: Aaron would approach one of the people and say "The other person sent me to tell you that he apologizes and is truly sorry for the way he acted towards you." Then he would go to the other person and say the same thing. The next time the two people met on the street, they would ask each other for forgiveness.
Even when it is permitted to lie, one should avoid it if possible, as illustrated by the following incident in the Talmud. The wife of the great Talmudic sage Rav always did the opposite of what he requested. If Rav asked for lentils she made beans, if he asked for beans she made lentils. When Rav's son, Chiya, grew up, he tried to correct the situation. Chiya told his mother the opposite of what his father wanted, thereby tricking her into making the correct food. Rav, realizing what Chiya had done, chastised him by quoting the verse: "They have taught their tongues to speak falsehood." Rav meant that a person should avoid lying even where it is permitted, lest he become accustomed to lying and lose his integrity.
Rabbi Yona Girundi in his classic "The Gates of Repentance" enumerates nine different levels of falsifying, beginning with dishonesty in crime and monetary matters and ending with a few types of "white lie." I very highly recommend the study of this passage.