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	$208.42	4.846%	$218.52	$218.52	$218.50	$218.50
Purchase #2	$214.94	5.175%	$226.0631	$226.06	$226.05	$226.10
Purchase #3	$81.64	11.388%	$90.9372	$90.94	$90.95	$90.90
Purchase #4	$86.98	9.597%	$95.3275	$95.33	$95.35	$95.30
Purchase #5	$183.45	10.824%	$203.3066	$203.31	$203.30	$203.30
Purchase #6	$62.49	5.232%	$65.7595	$65.76	$65.75	$65.80
Purchase #7	$141.77	9.396%	$155.0907	$155.09	$155.10	$155.10
7 purchase totals =	$979.69		$1,055.0046	$1,055.01	$1,055.00	$1,055.00