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	$177.51	10.468%	$196.0917	$196.09	$196.10	$196.10
Purchase #2	$160.29	6.339%	$170.4508	$170.45	$170.45	$170.50
Purchase #3	$44.62	4.467%	$46.6132	$46.61	$46.60	$46.60
Purchase #4	$203.27	5.851%	$215.1633	$215.16	$215.15	$215.20
Purchase #5	$167.61	12.677%	$188.8579	$188.86	$188.85	$188.90
Purchase #6	$217.96	11.743%	$243.555	$243.56	$243.55	$243.60
Purchase #7	$229.40	3.633%	$237.7341	$237.73	$237.75	$237.70
7 purchase totals =	$1,200.66		$1,298.4660	$1,298.46	$1,298.45	$1,298.60