You have a couple of options, and I'm not sure which one is the most efficient. I suspect the second one is.
Code:
WHERE Right(Format([qryUnmatched].[Amount],"0.00"),4)="0.00")
The format gives you at least three numeric digits plus the decimal point, so the comparison should work correctly.
Code:
WHERE ( ([qryUnmatched].[Amount]) = 10*INT(([qryUnmatched].[Amount])/10) )
The 10*INT(X/10) leaves zeroes in the ones place and the decimals, so it will only equal X if those digits were previously zero.