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	$193.29	12.346%	$217.1536	$217.15	$217.15	$217.20
Purchase #2	$145.48	8.723%	$158.1702	$158.17	$158.15	$158.20
Purchase #3	$22.83	6.310%	$24.2706	$24.27	$24.25	$24.30
Purchase #4	$180.82	4.328%	$188.6459	$188.65	$188.65	$188.60
Purchase #5	$111.90	6.257%	$118.9016	$118.90	$118.90	$118.90
Purchase #6	$156.30	11.578%	$174.3964	$174.40	$174.40	$174.40
Purchase #7	$214.72	10.790%	$237.8883	$237.89	$237.90	$237.90
7 purchase totals =	$1,025.34		$1,119.4266	$1,119.43	$1,119.40	$1,119.50