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	$165.72	9.467%	$181.4087	$181.41	$181.40	$181.40
Purchase #2	$111.28	9.528%	$121.8828	$121.88	$121.90	$121.90
Purchase #3	$88.81	12.112%	$99.5667	$99.57	$99.55	$99.60
Purchase #4	$51.25	12.251%	$57.5286	$57.53	$57.55	$57.50
Purchase #5	$233.38	8.643%	$253.551	$253.55	$253.55	$253.60
Purchase #6	$57.57	13.244%	$65.1946	$65.19	$65.20	$65.20
Purchase #7	$213.61	11.628%	$238.4486	$238.45	$238.45	$238.40
7 purchase totals =	$921.62		$1,017.5810	$1,017.58	$1,017.60	$1,017.60