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	$232.81	13.161%	$263.4501	$263.45	$263.45	$263.50
Purchase #2	$147.84	11.677%	$165.1033	$165.10	$165.10	$165.10
Purchase #3	$63.96	12.102%	$71.7004	$71.70	$71.70	$71.70
Purchase #4	$102.95	13.349%	$116.6928	$116.69	$116.70	$116.70
Purchase #5	$169.63	11.651%	$189.3936	$189.39	$189.40	$189.40
Purchase #6	$146.70	4.197%	$152.857	$152.86	$152.85	$152.90
Purchase #7	$211.53	5.495%	$223.1536	$223.15	$223.15	$223.20
7 purchase totals =	$1,075.42		$1,182.3508	$1,182.34	$1,182.35	$1,182.50