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	$225.67	7.455%	$242.4937	$242.49	$242.50	$242.50
Purchase #2	$210.32	7.701%	$226.5167	$226.52	$226.50	$226.50
Purchase #3	$196.92	11.450%	$219.4673	$219.47	$219.45	$219.50
Purchase #4	$172.57	10.159%	$190.1014	$190.10	$190.10	$190.10
Purchase #5	$128.67	4.219%	$134.0986	$134.10	$134.10	$134.10
Purchase #6	$222.66	8.632%	$241.88	$241.88	$241.90	$241.90
Purchase #7	$173.86	13.148%	$196.7191	$196.72	$196.70	$196.70
7 purchase totals =	$1,330.67		$1,451.2768	$1,451.28	$1,451.25	$1,451.30