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	$184.66	6.173%	$196.0591	$196.06	$196.05	$196.10
Purchase #2	$48.41	8.358%	$52.4561	$52.46	$52.45	$52.50
Purchase #3	$241.61	3.619%	$250.3539	$250.35	$250.35	$250.40
Purchase #4	$87.48	7.559%	$94.0926	$94.09	$94.10	$94.10
Purchase #5	$169.67	11.744%	$189.596	$189.60	$189.60	$189.60
Purchase #6	$220.45	3.202%	$227.5088	$227.51	$227.50	$227.50
Purchase #7	$55.87	11.416%	$62.2481	$62.25	$62.25	$62.20
7 purchase totals =	$1,008.15		$1,072.3146	$1,072.32	$1,072.30	$1,072.40