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	$234.79	11.778%	$262.4436	$262.44	$262.45	$262.40
Purchase #2	$10.41	13.652%	$11.8312	$11.83	$11.85	$11.80
Purchase #3	$196.60	13.251%	$222.6515	$222.65	$222.65	$222.70
Purchase #4	$54.99	7.836%	$59.299	$59.30	$59.30	$59.30
Purchase #5	$185.45	13.411%	$210.3207	$210.32	$210.30	$210.30
Purchase #6	$64.87	4.327%	$67.6769	$67.68	$67.70	$67.70
Purchase #7	$218.69	8.223%	$236.6729	$236.67	$236.65	$236.70
7 purchase totals =	$965.80		$1,070.8958	$1,070.89	$1,070.90	$1,070.90