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	$62.54	7.527%	$67.2474	$67.25	$67.25	$67.20
Purchase #2	$19.59	10.545%	$21.6558	$21.66	$21.65	$21.70
Purchase #3	$34.26	13.639%	$38.9327	$38.93	$38.95	$38.90
Purchase #4	$114.64	13.788%	$130.4466	$130.45	$130.45	$130.40
Purchase #5	$132.85	6.812%	$141.8997	$141.90	$141.90	$141.90
Purchase #6	$35.30	11.198%	$39.2529	$39.25	$39.25	$39.30
Purchase #7	$22.82	6.713%	$24.3519	$24.35	$24.35	$24.40
7 purchase totals =	$422.00		$463.7870	$463.79	$463.80	$463.80