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	$172.27	13.808%	$196.057	$196.06	$196.05	$196.10
Purchase #2	$199.94	5.256%	$210.4488	$210.45	$210.45	$210.40
Purchase #3	$165.44	4.588%	$173.0304	$173.03	$173.05	$173.00
Purchase #4	$207.68	10.612%	$229.719	$229.72	$229.70	$229.70
Purchase #5	$169.78	9.590%	$186.0619	$186.06	$186.05	$186.10
Purchase #6	$50.86	8.733%	$55.3016	$55.30	$55.30	$55.30
Purchase #7	$182.93	11.468%	$203.9084	$203.91	$203.90	$203.90
7 purchase totals =	$1,148.90		$1,254.5271	$1,254.53	$1,254.50	$1,254.50