The 5th Amendment protection against self-incrimination only applies to testifying in court regarding criminal charges. (My rememberer may be fuzzy, but I seem to want to say that at one time it was not even extended to testifying at a Grand Jury. My rememberer could be wrong, though.)
http://legal-dictionary.thefreedictionary.com/fifth+amendment
The U.S. Supreme Court has interpreted the Self-Incrimination Clause more broadly than many of the Framers probably would have. miranda v. arizona, 384 U.S. 436, 86 S. Ct. 1602, 16 L. Ed. 2d 694 (1966), illustrates this point. In Miranda the Court held that any statements made by defendants while in police custody before trial will be inadmissible during prosecution unless the police first warn the defendants that they have (1) the right to remain silent, (2) the right to consult an attorney before being questioned by the police, (3) the right to have an attorney present during police questioning, (4) the right to a court-appointed attorney if they cannot afford one, and (5) the right to be informed that any statements they do make can and will be used in their prosecution. Although the Miranda warnings are not provided in the Fifth Amendment's Self-Incrimination Clause, the Court has ruled that they constitute an essential part of a judicially created buffer zone that is necessary to protect rights that are specifically set forth in the Constitution.
In Dickerson v. United States 530 U.S. 428, 120 S. Ct. 2326, 147 L. Ed.2d 405 (2000), the U.S. Supreme Court concluded that the Miranda decision was based on Fifth Amendment principles and therefore that it could not be over-turned legislatively. Congressional anger at the Miranda decision had led to the passage in 1968 of a law, 18 U.S.C.A. § 3501, that had restored voluntariness as the test for admitting confessions in federal court. However, the United States department of justice, under attorneys general of both major political parties, has refused to enforce the provision, believing the law to be unconstitutional. The law lay dormant until the Fourth Circuit Court of Appeals ruled in 1999 that Congress had the constitutional authority to pass the law. Chief Justice william rehnquist, a frequent critic of the Miranda decision, joined the majority in rejecting the Fourth Circuit interpretation. Although members of the Court might not agree with the reasoning and the rule of Miranda, Rehnquist acknowledged the essential place that Miranda has in U.S. law and society. He pointed out the importance that the judicial system places on Stare Decisis, a concept that counsels courts to honor judicial precedents to ensure stability and predictability in decision-making. A court should only overrule its case precedents if there is, in Rehnquist's words, "special justification." The Court in Dickerson concluded there were no special justifications.