Does the Catholic Church believe in tithing (ten percent off the top) or should we only give what we are able to give?
The Church does not require the faithful to tithe a certain percentage of their income to the Church. What the Church does require is as follows:
Catechism of the Catholic Church 2043
“The fifth precept (“You shall help to provide for the needs of the Church”) means that the faithful are obliged to assist with the material needs of the Church, each according to his own ability.
The faithful also have the duty of providing for the material needs of the Church, each according to his own abilities. (Catechism of the Catholic Church 2043)
Code of Canon Law no 222:
“The Christian faithful are obliged to assist with the needs of the Church so that the Church has what is necessary for divine worship, for apostolic works and works of charity and for the decent sustenance of ministers. They are also obliged to promote social justice and, mindful of the precept of the Lord, to assist the poor from their own resources.”
For a more in-depth answer on this topic, I recommend the following article
Tithing: An Old Law or Today’s Standard for Giving? by Phil Lenahan