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	$218.42	12.520%	$245.7662	$245.77	$245.75	$245.80
Purchase #2	$236.85	7.688%	$255.059	$255.06	$255.05	$255.10
Purchase #3	$6.91	10.222%	$7.6163	$7.62	$7.60	$7.60
Purchase #4	$54.99	6.163%	$58.379	$58.38	$58.40	$58.40
Purchase #5	$164.93	8.203%	$178.4592	$178.46	$178.45	$178.50
Purchase #6	$189.90	3.302%	$196.1705	$196.17	$196.15	$196.20
Purchase #7	$94.64	9.444%	$103.5778	$103.58	$103.60	$103.60
7 purchase totals =	$966.64		$1,045.0280	$1,045.04	$1,045.00	$1,045.20