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	$204.53	3.484%	$211.6558	$211.66	$211.65	$211.70
Purchase #2	$11.80	12.466%	$13.271	$13.27	$13.25	$13.30
Purchase #3	$184.37	3.526%	$190.8709	$190.87	$190.85	$190.90
Purchase #4	$172.71	10.864%	$191.4732	$191.47	$191.45	$191.50
Purchase #5	$140.55	10.427%	$155.2051	$155.21	$155.20	$155.20
Purchase #6	$86.91	10.196%	$95.7713	$95.77	$95.75	$95.80
Purchase #7	$207.78	5.627%	$219.4718	$219.47	$219.45	$219.50
7 purchase totals =	$1,008.65		$1,077.7191	$1,077.72	$1,077.60	$1,077.90