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	$105.94	12.693%	$119.387	$119.39	$119.40	$119.40
Purchase #2	$38.80	5.344%	$40.8735	$40.87	$40.85	$40.90
Purchase #3	$79.50	8.358%	$86.1446	$86.14	$86.15	$86.10
Purchase #4	$19.51	5.632%	$20.6088	$20.61	$20.60	$20.60
Purchase #5	$30.72	10.141%	$33.8353	$33.84	$33.85	$33.80
Purchase #6	$211.62	5.695%	$223.6718	$223.67	$223.65	$223.70
Purchase #7	$44.85	13.168%	$50.7558	$50.76	$50.75	$50.80
7 purchase totals =	$530.94		$575.2768	$575.28	$575.25	$575.30