LDS Tithing Requirement
No, there is no losing of your membership over tithing. However, there is strong encouragement from leadership, because there is no progressing without tithing. For instance, a member cannot attend the temple without tithing, and that is considered a major step in one's eternal progression.
There are specific blessings associated with paying tithing, also. So we are in effect denying ourselves the blessings if we do not obey the commandment to tithe.