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	$148.66	8.814%	$161.7629	$161.76	$161.75	$161.80
Purchase #2	$59.78	7.489%	$64.2569	$64.26	$64.25	$64.30
Purchase #3	$48.67	5.141%	$51.1721	$51.17	$51.15	$51.20
Purchase #4	$75.34	4.437%	$78.6828	$78.68	$78.70	$78.70
Purchase #5	$151.47	4.788%	$158.7224	$158.72	$158.70	$158.70
Purchase #6	$19.42	8.660%	$21.1018	$21.10	$21.10	$21.10
Purchase #7	$81.88	9.434%	$89.6046	$89.60	$89.60	$89.60
7 purchase totals =	$585.22		$625.3035	$625.29	$625.25	$625.40