Iran Nonproliferation Enforcement Act of 2005 - Amends the Iran Nonproliferation Act of 2000 to: (1) make sanctions mandatory, and impose a minimum two-year sanction; (2) subject controlling and subsidiary companies of a foreign person to sanctions; (3) expand sanctions to include prohibitions on U.S. investment, financing, and financial assistance; and (4) expand the justification requirements for a presidential national security waiver of sanctions.