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	$187.99	4.487%	$196.4251	$196.43	$196.45	$196.40
Purchase #2	$81.45	8.674%	$88.515	$88.52	$88.50	$88.50
Purchase #3	$165.43	10.156%	$182.2311	$182.23	$182.25	$182.20
Purchase #4	$132.52	13.242%	$150.0683	$150.07	$150.05	$150.10
Purchase #5	$125.52	4.846%	$131.6027	$131.60	$131.60	$131.60
Purchase #6	$197.84	12.282%	$222.1387	$222.14	$222.15	$222.10
Purchase #7	$72.62	8.368%	$78.6968	$78.70	$78.70	$78.70
7 purchase totals =	$963.37		$1,049.6777	$1,049.69	$1,049.70	$1,049.60