Religious context:
* Offering: This is a general term for a contribution to a religious organization.
* Donation: Similar to offering, but can be more specific to a charitable contribution.
* Tenth: This emphasizes the historical meaning of a tithe as one-tenth of one's income.
* Oblation: This is a more formal term for a religious offering.
Non-religious context:
* Contribution: This is a general term for any contribution, whether financial or otherwise.
* Share: This emphasizes that the amount given is a portion of something larger.
* Payment: This emphasizes the aspect of giving something in exchange for something else.
The best synonym for "tithe" will depend on the specific context in which you are using the word.