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	$162.43	4.423%	$169.6143	$169.61	$169.60	$169.60
Purchase #2	$150.76	7.686%	$162.3474	$162.35	$162.35	$162.30
Purchase #3	$32.88	7.832%	$35.4552	$35.46	$35.45	$35.50
Purchase #4	$155.27	13.277%	$175.8852	$175.89	$175.90	$175.90
Purchase #5	$150.37	8.203%	$162.7049	$162.70	$162.70	$162.70
Purchase #6	$248.41	12.325%	$279.0265	$279.03	$279.05	$279.00
Purchase #7	$145.47	4.106%	$151.443	$151.44	$151.45	$151.40
7 purchase totals =	$1,045.59		$1,136.4765	$1,136.48	$1,136.50	$1,136.40