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	$168.27	5.379%	$177.3212	$177.32	$177.30	$177.30
Purchase #2	$150.96	13.341%	$171.0996	$171.10	$171.10	$171.10
Purchase #3	$165.67	4.718%	$173.4863	$173.49	$173.50	$173.50
Purchase #4	$218.41	13.497%	$247.8888	$247.89	$247.90	$247.90
Purchase #5	$103.64	10.184%	$114.1947	$114.19	$114.20	$114.20
Purchase #6	$44.89	8.310%	$48.6204	$48.62	$48.60	$48.60
Purchase #7	$87.99	13.589%	$99.947	$99.95	$99.95	$99.90
7 purchase totals =	$939.83		$1,032.5580	$1,032.56	$1,032.55	$1,032.50