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	$76.75	13.593%	$87.1826	$87.18	$87.20	$87.20
Purchase #2	$18.69	6.462%	$19.8977	$19.90	$19.90	$19.90
Purchase #3	$51.50	6.797%	$55.0005	$55.00	$55.00	$55.00
Purchase #4	$19.95	6.233%	$21.1935	$21.19	$21.20	$21.20
Purchase #5	$79.89	8.305%	$86.5249	$86.52	$86.50	$86.50
Purchase #6	$149.28	5.129%	$156.9366	$156.94	$156.95	$156.90
Purchase #7	$35.33	4.333%	$36.8608	$36.86	$36.85	$36.90
7 purchase totals =	$431.39		$463.5966	$463.59	$463.60	$463.60