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	$106.29	5.216%	$111.8341	$111.83	$111.85	$111.80
Purchase #2	$99.50	11.419%	$110.8619	$110.86	$110.85	$110.90
Purchase #3	$182.53	7.733%	$196.645	$196.65	$196.65	$196.60
Purchase #4	$132.71	11.544%	$148.03	$148.03	$148.05	$148.00
Purchase #5	$132.92	8.157%	$143.7623	$143.76	$143.75	$143.80
Purchase #6	$163.74	10.603%	$181.1014	$181.10	$181.10	$181.10
Purchase #7	$126.96	11.659%	$141.7623	$141.76	$141.75	$141.80
7 purchase totals =	$944.65		$1,033.9970	$1,033.99	$1,034.00	$1,034.00