a penny
Matthew 18:28
But the same servant went out and found one of his fellow servants who owed him a hundred pence. And he laid hands on him, and took him by the throat, saying, `Pay me what thou owest.'
Matthew 20:2
And when he had agreed with the laborers for a penny a day, he sent them into his vineyard.
Revelation 6:6
And I heard a voice in the midst of the four living beings say, "A measure of wheat for a penny, and three measures of barley for a penny; and see thou hurt not the oil and the wine!"