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	$199.35	8.833%	$216.9586	$216.96	$216.95	$217.00
Purchase #2	$43.44	5.698%	$45.9152	$45.92	$45.90	$45.90
Purchase #3	$177.80	4.373%	$185.5752	$185.58	$185.60	$185.60
Purchase #4	$100.59	8.145%	$108.7831	$108.78	$108.80	$108.80
Purchase #5	$61.96	7.846%	$66.8214	$66.82	$66.80	$66.80
Purchase #6	$226.32	8.471%	$245.4916	$245.49	$245.50	$245.50
Purchase #7	$182.81	3.124%	$188.521	$188.52	$188.50	$188.50
7 purchase totals =	$992.27		$1,058.0661	$1,058.07	$1,058.05	$1,058.10