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	$162.41	3.562%	$168.195	$168.20	$168.20	$168.20
Purchase #2	$18.74	11.723%	$20.9369	$20.94	$20.95	$20.90
Purchase #3	$218.85	10.526%	$241.8862	$241.89	$241.90	$241.90
Purchase #4	$249.44	10.249%	$275.0051	$275.01	$275.00	$275.00
Purchase #5	$60.59	8.144%	$65.5244	$65.52	$65.50	$65.50
Purchase #6	$155.95	4.302%	$162.659	$162.66	$162.65	$162.70
Purchase #7	$152.31	7.104%	$163.1301	$163.13	$163.15	$163.10
7 purchase totals =	$1,018.29		$1,097.3367	$1,097.35	$1,097.35	$1,097.30