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	$193.51	11.758%	$216.2629	$216.26	$216.25	$216.30
Purchase #2	$64.32	5.510%	$67.864	$67.86	$67.85	$67.90
Purchase #3	$201.55	11.648%	$225.0265	$225.03	$225.05	$225.00
Purchase #4	$100.81	10.176%	$111.0684	$111.07	$111.05	$111.10
Purchase #5	$105.39	8.836%	$114.7023	$114.70	$114.70	$114.70
Purchase #6	$22.44	9.430%	$24.5561	$24.56	$24.55	$24.60
Purchase #7	$182.89	12.315%	$205.4129	$205.41	$205.40	$205.40
7 purchase totals =	$870.91		$964.8931	$964.89	$964.85	$965.00