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	$208.82	5.132%	$219.5366	$219.54	$219.55	$219.50
Purchase #2	$241.79	5.612%	$255.3593	$255.36	$255.35	$255.40
Purchase #3	$92.49	3.460%	$95.6902	$95.69	$95.70	$95.70
Purchase #4	$77.87	8.222%	$84.2725	$84.27	$84.25	$84.30
Purchase #5	$238.82	6.144%	$253.4931	$253.49	$253.50	$253.50
Purchase #6	$132.89	7.326%	$142.6255	$142.63	$142.65	$142.60
Purchase #7	$248.95	6.139%	$264.233	$264.23	$264.25	$264.20
7 purchase totals =	$1,241.63		$1,315.2102	$1,315.21	$1,315.25	$1,315.20