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	$208.75	6.201%	$221.6946	$221.69	$221.70	$221.70
Purchase #2	$241.60	6.166%	$256.4971	$256.50	$256.50	$256.50
Purchase #3	$76.28	7.611%	$82.0857	$82.09	$82.10	$82.10
Purchase #4	$236.51	13.214%	$267.7624	$267.76	$267.75	$267.80
Purchase #5	$158.73	8.415%	$172.0871	$172.09	$172.10	$172.10
Purchase #6	$242.47	10.459%	$267.8299	$267.83	$267.85	$267.80
Purchase #7	$33.39	6.459%	$35.5467	$35.55	$35.55	$35.50
7 purchase totals =	$1,197.73		$1,303.5035	$1,303.51	$1,303.55	$1,303.50