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	$112.43	3.745%	$116.6405	$116.64	$116.65	$116.60
Purchase #2	$214.42	3.723%	$222.4029	$222.40	$222.40	$222.40
Purchase #3	$123.77	5.705%	$130.8311	$130.83	$130.85	$130.80
Purchase #4	$116.64	7.159%	$124.9903	$124.99	$125.00	$125.00
Purchase #5	$205.82	8.665%	$223.6543	$223.65	$223.65	$223.70
Purchase #6	$106.76	5.741%	$112.8891	$112.89	$112.90	$112.90
Purchase #7	$11.46	8.281%	$12.409	$12.41	$12.40	$12.40
7 purchase totals =	$891.30		$943.8172	$943.81	$943.85	$943.80