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	$190.44	7.476%	$204.6773	$204.68	$204.70	$204.70
Purchase #2	$7.26	3.226%	$7.4942	$7.49	$7.50	$7.50
Purchase #3	$62.45	6.650%	$66.6029	$66.60	$66.60	$66.60
Purchase #4	$52.51	9.132%	$57.3052	$57.31	$57.30	$57.30
Purchase #5	$209.89	4.457%	$219.2448	$219.24	$219.25	$219.20
Purchase #6	$80.75	11.131%	$89.7383	$89.74	$89.75	$89.70
Purchase #7	$36.25	5.107%	$38.1013	$38.10	$38.10	$38.10
7 purchase totals =	$639.55		$683.1640	$683.16	$683.20	$683.10