There is only one file type that uses the .TIG extension:
TI Connect Backup File
Backup file created by TI Connect, an application used to manage data on Texas Instruments (TI) calculators; stores a full backup of the data on the calculator, including the applications and settings; used for restoring a calculator's state when connected via TI Connect.
TIG files can be used for restoring the factory installation state if programs are accidentally deleted. Consult the TI website to acquire the appropriate file for your calculator version.
A TIG file can be opened by programs that can open .ZIP files, such as Smith Micro StuffIt Expander.
NOTE: TIG files support TI devices such as the TI-83 and TI-84 series calculators.
Updated: July 19, 2014