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	$168.37	6.599%	$179.4807	$179.48	$179.50	$179.50
Purchase #2	$183.93	4.126%	$191.519	$191.52	$191.50	$191.50
Purchase #3	$19.54	5.468%	$20.6084	$20.61	$20.60	$20.60
Purchase #4	$93.61	9.209%	$102.2305	$102.23	$102.25	$102.20
Purchase #5	$159.38	8.600%	$173.0867	$173.09	$173.10	$173.10
Purchase #6	$213.96	6.325%	$227.493	$227.49	$227.50	$227.50
Purchase #7	$197.50	11.550%	$220.3113	$220.31	$220.30	$220.30
7 purchase totals =	$1,036.29		$1,114.7296	$1,114.73	$1,114.75	$1,114.70