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	$69.30	4.381%	$72.336	$72.34	$72.35	$72.30
Purchase #2	$148.69	6.297%	$158.053	$158.05	$158.05	$158.10
Purchase #3	$24.74	5.756%	$26.164	$26.16	$26.15	$26.20
Purchase #4	$205.89	9.468%	$225.3837	$225.38	$225.40	$225.40
Purchase #5	$238.80	13.334%	$270.6416	$270.64	$270.65	$270.60
Purchase #6	$158.50	7.768%	$170.8123	$170.81	$170.80	$170.80
Purchase #7	$74.49	5.756%	$78.7776	$78.78	$78.80	$78.80
7 purchase totals =	$920.41		$1,002.1682	$1,002.16	$1,002.20	$1,002.20