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	$87.47	7.835%	$94.3233	$94.32	$94.30	$94.30
Purchase #2	$112.50	4.824%	$117.927	$117.93	$117.95	$117.90
Purchase #3	$51.60	8.703%	$56.0907	$56.09	$56.10	$56.10
Purchase #4	$96.74	3.859%	$100.4732	$100.47	$100.45	$100.50
Purchase #5	$155.33	9.211%	$169.6374	$169.64	$169.65	$169.60
Purchase #6	$203.52	4.501%	$212.6804	$212.68	$212.70	$212.70
Purchase #7	$246.28	7.792%	$265.4701	$265.47	$265.45	$265.50
7 purchase totals =	$953.44		$1,016.6021	$1,016.60	$1,016.60	$1,016.60