Do we need to enter the fractional (decimal) amount for W2 related boxes on Form 1040 like box1,3,5? For example, $XX,XXX.YY, is the YY required to be entered?

[yatoshura]

If my W-2 address is incorrect, do I need a corrected one (does the IRS require?) from my employer or can I just enter the correct address on Form 1040 when filing my 2015 tax return?

Is it normal to only have a W-2 box 15 (for my state - Washington) without boxes 16-20?

[KarenL2]

You can just round up or down and do not have to enter the fractional amounts. 

You will enter your W-2 address exactly as it is on the form itself. You do not need a corrected W-2, but it's good to have it match the one the IRS received.  It's okay that the mailing address on your Form 1040 is different than your W-2.

Also, yes it is normal to have just the state in Box 15 with nothing else for the state sections when you have a state that has no income taxes.