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	$86.25	10.130%	$94.9871	$94.99	$95.00	$95.00
Purchase #2	$91.69	5.852%	$97.0557	$97.06	$97.05	$97.10
Purchase #3	$227.61	13.560%	$258.4739	$258.47	$258.45	$258.50
Purchase #4	$214.46	11.313%	$238.7219	$238.72	$238.70	$238.70
Purchase #5	$74.78	4.469%	$78.1219	$78.12	$78.10	$78.10
Purchase #6	$194.29	7.643%	$209.1396	$209.14	$209.15	$209.10
Purchase #7	$52.68	3.630%	$54.5923	$54.59	$54.60	$54.60
7 purchase totals =	$941.76		$1,031.0924	$1,031.09	$1,031.05	$1,031.10