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	$57.71	8.237%	$62.4636	$62.46	$62.45	$62.50
Purchase #2	$12.73	7.454%	$13.6789	$13.68	$13.70	$13.70
Purchase #3	$76.55	11.311%	$85.2086	$85.21	$85.20	$85.20
Purchase #4	$87.68	9.766%	$96.2428	$96.24	$96.25	$96.20
Purchase #5	$39.26	9.270%	$42.8994	$42.90	$42.90	$42.90
Purchase #6	$245.82	3.127%	$253.5068	$253.51	$253.50	$253.50
Purchase #7	$6.68	13.836%	$7.6042	$7.60	$7.60	$7.60
7 purchase totals =	$526.43		$561.6043	$561.60	$561.60	$561.60