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	$69.97	3.358%	$72.3196	$72.32	$72.30	$72.30
Purchase #2	$151.36	5.373%	$159.4926	$159.49	$159.50	$159.50
Purchase #3	$68.64	12.591%	$77.2825	$77.28	$77.30	$77.30
Purchase #4	$124.76	13.478%	$141.5752	$141.58	$141.60	$141.60
Purchase #5	$63.99	5.436%	$67.4685	$67.47	$67.45	$67.50
Purchase #6	$142.46	9.120%	$155.4524	$155.45	$155.45	$155.50
Purchase #7	$37.95	6.176%	$40.2938	$40.29	$40.30	$40.30
7 purchase totals =	$659.13		$713.8846	$713.88	$713.90	$714.00