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	$213.68	3.368%	$220.8767	$220.88	$220.90	$220.90
Purchase #2	$95.25	5.485%	$100.4745	$100.47	$100.45	$100.50
Purchase #3	$130.25	5.578%	$137.5153	$137.52	$137.50	$137.50
Purchase #4	$11.30	3.269%	$11.6694	$11.67	$11.65	$11.70
Purchase #5	$245.86	4.500%	$256.9237	$256.92	$256.90	$256.90
Purchase #6	$207.69	8.685%	$225.7279	$225.73	$225.75	$225.70
Purchase #7	$72.46	7.109%	$77.6112	$77.61	$77.60	$77.60
7 purchase totals =	$976.49		$1,030.7987	$1,030.80	$1,030.75	$1,030.80