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	$104.54	13.606%	$118.7637	$118.76	$118.75	$118.80
Purchase #2	$206.86	10.552%	$228.6879	$228.69	$228.70	$228.70
Purchase #3	$125.44	5.619%	$132.4885	$132.49	$132.50	$132.50
Purchase #4	$190.45	3.258%	$196.6549	$196.65	$196.65	$196.70
Purchase #5	$54.87	13.263%	$62.1474	$62.15	$62.15	$62.10
Purchase #6	$128.90	13.858%	$146.763	$146.76	$146.75	$146.80
Purchase #7	$213.83	12.532%	$240.6272	$240.63	$240.65	$240.60
7 purchase totals =	$1,024.89		$1,126.1326	$1,126.13	$1,126.15	$1,126.20