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	$62.33	5.286%	$65.6248	$65.62	$65.60	$65.60
Purchase #2	$112.59	5.253%	$118.5044	$118.50	$118.50	$118.50
Purchase #3	$150.63	3.685%	$156.1807	$156.18	$156.20	$156.20
Purchase #4	$123.43	6.141%	$131.0098	$131.01	$131.00	$131.00
Purchase #5	$49.36	9.790%	$54.1923	$54.19	$54.20	$54.20
Purchase #6	$148.53	9.471%	$162.5973	$162.60	$162.60	$162.60
Purchase #7	$111.28	5.855%	$117.7954	$117.80	$117.80	$117.80
7 purchase totals =	$758.15		$805.9047	$805.90	$805.90	$805.90