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	$215.46	6.870%	$230.2621	$230.26	$230.25	$230.30
Purchase #2	$106.26	4.578%	$111.1246	$111.12	$111.10	$111.10
Purchase #3	$145.96	6.436%	$155.354	$155.35	$155.35	$155.40
Purchase #4	$160.92	13.654%	$182.892	$182.89	$182.90	$182.90
Purchase #5	$8.89	11.583%	$9.9197	$9.92	$9.90	$9.90
Purchase #6	$210.90	8.379%	$228.5713	$228.57	$228.55	$228.60
Purchase #7	$124.48	3.162%	$128.4161	$128.42	$128.40	$128.40
7 purchase totals =	$972.87		$1,046.5398	$1,046.53	$1,046.45	$1,046.60