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	$248.42	8.451%	$269.414	$269.41	$269.40	$269.40
Purchase #2	$145.26	3.189%	$149.8923	$149.89	$149.90	$149.90
Purchase #3	$212.41	8.698%	$230.8854	$230.89	$230.90	$230.90
Purchase #4	$54.82	4.329%	$57.1932	$57.19	$57.20	$57.20
Purchase #5	$178.94	9.696%	$196.29	$196.29	$196.30	$196.30
Purchase #6	$182.25	5.119%	$191.5794	$191.58	$191.60	$191.60
Purchase #7	$55.60	3.349%	$57.462	$57.46	$57.45	$57.50
7 purchase totals =	$1,077.70		$1,152.7163	$1,152.71	$1,152.75	$1,152.80