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	$146.46	10.636%	$162.0375	$162.04	$162.05	$162.00
Purchase #2	$116.63	9.373%	$127.5617	$127.56	$127.55	$127.60
Purchase #3	$122.25	4.354%	$127.5728	$127.57	$127.55	$127.60
Purchase #4	$209.94	13.602%	$238.496	$238.50	$238.50	$238.50
Purchase #5	$91.87	10.257%	$101.2931	$101.29	$101.30	$101.30
Purchase #6	$59.65	4.181%	$62.144	$62.14	$62.15	$62.10
Purchase #7	$154.61	12.343%	$173.6935	$173.69	$173.70	$173.70
7 purchase totals =	$901.41		$992.7986	$992.79	$992.80	$992.80