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	$223.70	6.252%	$237.6857	$237.69	$237.70	$237.70
Purchase #2	$199.52	5.377%	$210.2482	$210.25	$210.25	$210.20
Purchase #3	$63.33	6.607%	$67.5142	$67.51	$67.50	$67.50
Purchase #4	$238.86	5.754%	$252.604	$252.60	$252.60	$252.60
Purchase #5	$75.46	4.643%	$78.9636	$78.96	$78.95	$79.00
Purchase #6	$146.29	6.685%	$156.0695	$156.07	$156.05	$156.10
Purchase #7	$120.53	9.365%	$131.8176	$131.82	$131.80	$131.80
7 purchase totals =	$1,067.69		$1,134.9028	$1,134.90	$1,134.85	$1,134.90