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	$83.94	12.872%	$94.7448	$94.74	$94.75	$94.70
Purchase #2	$85.73	10.342%	$94.5962	$94.60	$94.60	$94.60
Purchase #3	$61.92	8.273%	$67.0426	$67.04	$67.05	$67.00
Purchase #4	$232.89	10.305%	$256.8893	$256.89	$256.90	$256.90
Purchase #5	$248.77	13.615%	$282.64	$282.64	$282.65	$282.60
Purchase #6	$158.29	5.639%	$167.216	$167.22	$167.20	$167.20
Purchase #7	$110.37	12.725%	$124.4146	$124.41	$124.40	$124.40
7 purchase totals =	$981.91		$1,087.5435	$1,087.54	$1,087.55	$1,087.40