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	$212.43	10.650%	$235.0538	$235.05	$235.05	$235.10
Purchase #2	$5.52	12.263%	$6.1969	$6.20	$6.20	$6.20
Purchase #3	$181.30	5.180%	$190.6913	$190.69	$190.70	$190.70
Purchase #4	$152.72	3.863%	$158.6196	$158.62	$158.60	$158.60
Purchase #5	$107.28	4.515%	$112.1237	$112.12	$112.10	$112.10
Purchase #6	$190.86	5.162%	$200.7122	$200.71	$200.70	$200.70
Purchase #7	$194.26	7.143%	$208.136	$208.14	$208.15	$208.10
7 purchase totals =	$1,044.37		$1,111.5335	$1,111.53	$1,111.50	$1,111.50