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	$197.68	8.569%	$214.6192	$214.62	$214.60	$214.60
Purchase #2	$60.76	3.149%	$62.6733	$62.67	$62.65	$62.70
Purchase #3	$93.41	5.491%	$98.5391	$98.54	$98.55	$98.50
Purchase #4	$82.30	6.592%	$87.7252	$87.73	$87.75	$87.70
Purchase #5	$33.61	9.793%	$36.9014	$36.90	$36.90	$36.90
Purchase #6	$61.54	9.173%	$67.1851	$67.19	$67.20	$67.20
Purchase #7	$52.51	13.277%	$59.4818	$59.48	$59.50	$59.50
7 purchase totals =	$581.81		$627.1251	$627.13	$627.15	$627.10