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	$74.71	9.806%	$82.0361	$82.04	$82.05	$82.00
Purchase #2	$143.28	4.605%	$149.878	$149.88	$149.90	$149.90
Purchase #3	$245.90	10.449%	$271.5941	$271.59	$271.60	$271.60
Purchase #4	$108.32	5.817%	$114.621	$114.62	$114.60	$114.60
Purchase #5	$171.47	4.106%	$178.5106	$178.51	$178.50	$178.50
Purchase #6	$83.46	3.687%	$86.5372	$86.54	$86.55	$86.50
Purchase #7	$231.49	9.478%	$253.4306	$253.43	$253.45	$253.40
7 purchase totals =	$1,058.63		$1,136.6076	$1,136.61	$1,136.65	$1,136.50