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	$233.60	5.723%	$246.9689	$246.97	$246.95	$247.00
Purchase #2	$203.64	10.396%	$224.8104	$224.81	$224.80	$224.80
Purchase #3	$188.80	4.275%	$196.8712	$196.87	$196.85	$196.90
Purchase #4	$48.80	4.298%	$50.8974	$50.90	$50.90	$50.90
Purchase #5	$29.63	10.218%	$32.6576	$32.66	$32.65	$32.70
Purchase #6	$225.80	12.752%	$254.594	$254.59	$254.60	$254.60
Purchase #7	$88.86	7.339%	$95.3814	$95.38	$95.40	$95.40
7 purchase totals =	$1,019.13		$1,102.1809	$1,102.18	$1,102.15	$1,102.30