Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$177.43	3.718%	$184.0268	$184.03	$184.05	$184.00
Purchase #2	$182.68	12.432%	$205.3908	$205.39	$205.40	$205.40
Purchase #3	$195.32	9.505%	$213.8852	$213.89	$213.90	$213.90
Purchase #4	$127.61	13.600%	$144.965	$144.97	$144.95	$145.00
Purchase #5	$162.59	8.162%	$175.8606	$175.86	$175.85	$175.90
Purchase #6	$36.90	12.749%	$41.6044	$41.60	$41.60	$41.60
Purchase #7	$168.89	4.405%	$176.3296	$176.33	$176.35	$176.30
7 purchase totals =	$1,051.42		$1,142.0624	$1,142.07	$1,142.10	$1,142.10