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	$162.67	6.663%	$173.5087	$173.51	$173.50	$173.50
Purchase #2	$50.31	7.552%	$54.1094	$54.11	$54.10	$54.10
Purchase #3	$183.41	6.627%	$195.5646	$195.56	$195.55	$195.60
Purchase #4	$248.68	6.735%	$265.4286	$265.43	$265.45	$265.40
Purchase #5	$172.85	10.620%	$191.2067	$191.21	$191.20	$191.20
Purchase #6	$24.83	7.493%	$26.6905	$26.69	$26.70	$26.70
Purchase #7	$90.36	11.362%	$100.6267	$100.63	$100.65	$100.60
7 purchase totals =	$933.11		$1,007.1352	$1,007.14	$1,007.15	$1,007.10