Servicemembers Interest Rate Relief Act of 2005 - Amends the Servicemembers' Civil Relief Act to revise the six percent maximum annual interest rate to be charged on debts incurred by a servicemember, and his or her spouse jointly, before the servicemember enters into military service and continuing for the duration of such military service, to five percent in the case of any interest incurred during the period beginning on October 1, 2006, and ending on September 30, 2009.