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	$98.68	13.476%	$111.9781	$111.98	$112.00	$112.00
Purchase #2	$118.33	8.126%	$127.9455	$127.95	$127.95	$127.90
Purchase #3	$179.58	4.581%	$187.8066	$187.81	$187.80	$187.80
Purchase #4	$127.76	5.398%	$134.6565	$134.66	$134.65	$134.70
Purchase #5	$243.79	7.835%	$262.8909	$262.89	$262.90	$262.90
Purchase #6	$158.65	13.248%	$179.668	$179.67	$179.65	$179.70
Purchase #7	$10.92	11.135%	$12.1359	$12.14	$12.15	$12.10
7 purchase totals =	$937.71		$1,017.0815	$1,017.10	$1,017.10	$1,017.10