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	$87.67	8.449%	$95.0772	$95.08	$95.10	$95.10
Purchase #2	$109.60	12.682%	$123.4995	$123.50	$123.50	$123.50
Purchase #3	$145.93	10.763%	$161.6364	$161.64	$161.65	$161.60
Purchase #4	$55.59	10.816%	$61.6026	$61.60	$61.60	$61.60
Purchase #5	$27.56	5.193%	$28.9912	$28.99	$29.00	$29.00
Purchase #6	$96.35	8.304%	$104.3509	$104.35	$104.35	$104.40
Purchase #7	$162.69	10.103%	$179.1266	$179.13	$179.15	$179.10
7 purchase totals =	$685.39		$754.2844	$754.29	$754.35	$754.30