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	$57.98	6.149%	$61.5452	$61.55	$61.55	$61.50
Purchase #2	$12.89	5.665%	$13.6202	$13.62	$13.60	$13.60
Purchase #3	$80.63	5.644%	$85.1808	$85.18	$85.20	$85.20
Purchase #4	$112.85	12.644%	$127.1188	$127.12	$127.10	$127.10
Purchase #5	$18.36	6.504%	$19.5541	$19.55	$19.55	$19.60
Purchase #6	$191.34	9.763%	$210.0205	$210.02	$210.00	$210.00
Purchase #7	$186.55	10.499%	$206.1359	$206.14	$206.15	$206.10
7 purchase totals =	$660.60		$723.1755	$723.18	$723.15	$723.10