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	$164.47	5.218%	$173.052	$173.05	$173.05	$173.10
Purchase #2	$164.85	5.129%	$173.3052	$173.31	$173.30	$173.30
Purchase #3	$168.62	6.374%	$179.3678	$179.37	$179.35	$179.40
Purchase #4	$106.82	7.475%	$114.8048	$114.80	$114.80	$114.80
Purchase #5	$54.28	6.160%	$57.6236	$57.62	$57.60	$57.60
Purchase #6	$43.32	5.355%	$45.6398	$45.64	$45.65	$45.60
Purchase #7	$61.89	13.834%	$70.4519	$70.45	$70.45	$70.50
7 purchase totals =	$764.25		$814.2451	$814.24	$814.20	$814.30