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	$95.89	10.182%	$105.6535	$105.65	$105.65	$105.70
Purchase #2	$227.32	7.470%	$244.3008	$244.30	$244.30	$244.30
Purchase #3	$217.71	5.150%	$228.9221	$228.92	$228.90	$228.90
Purchase #4	$14.63	8.658%	$15.8967	$15.90	$15.90	$15.90
Purchase #5	$103.81	4.488%	$108.469	$108.47	$108.45	$108.50
Purchase #6	$212.79	10.738%	$235.6394	$235.64	$235.65	$235.60
Purchase #7	$106.71	4.808%	$111.8406	$111.84	$111.85	$111.80
7 purchase totals =	$978.86		$1,050.7221	$1,050.72	$1,050.70	$1,050.70