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	$102.94	11.348%	$114.6216	$114.62	$114.60	$114.60
Purchase #2	$17.28	11.354%	$19.242	$19.24	$19.25	$19.20
Purchase #3	$88.73	12.394%	$99.7272	$99.73	$99.75	$99.70
Purchase #4	$53.79	10.489%	$59.432	$59.43	$59.45	$59.40
Purchase #5	$125.46	5.710%	$132.6238	$132.62	$132.60	$132.60
Purchase #6	$249.63	7.298%	$267.848	$267.85	$267.85	$267.80
Purchase #7	$195.48	13.788%	$222.4328	$222.43	$222.45	$222.40
7 purchase totals =	$833.31		$915.9274	$915.92	$915.95	$915.70