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	$175.67	10.758%	$194.5686	$194.57	$194.55	$194.60
Purchase #2	$177.33	4.478%	$185.2708	$185.27	$185.25	$185.30
Purchase #3	$75.35	6.224%	$80.0398	$80.04	$80.05	$80.00
Purchase #4	$160.82	4.222%	$167.6098	$167.61	$167.60	$167.60
Purchase #5	$228.53	9.451%	$250.1284	$250.13	$250.15	$250.10
Purchase #6	$98.71	12.732%	$111.2778	$111.28	$111.30	$111.30
Purchase #7	$153.90	12.847%	$173.6715	$173.67	$173.65	$173.70
7 purchase totals =	$1,070.31		$1,162.5667	$1,162.57	$1,162.55	$1,162.60