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	$148.32	9.240%	$162.0248	$162.02	$162.00	$162.00
Purchase #2	$218.53	11.525%	$243.7156	$243.72	$243.70	$243.70
Purchase #3	$144.42	6.704%	$154.1019	$154.10	$154.10	$154.10
Purchase #4	$117.96	11.674%	$131.7307	$131.73	$131.75	$131.70
Purchase #5	$152.46	12.828%	$172.0176	$172.02	$172.00	$172.00
Purchase #6	$143.58	3.553%	$148.6814	$148.68	$148.70	$148.70
Purchase #7	$145.40	4.504%	$151.9488	$151.95	$151.95	$151.90
7 purchase totals =	$1,070.67		$1,164.2208	$1,164.22	$1,164.20	$1,164.10