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	$94.95	7.519%	$102.0893	$102.09	$102.10	$102.10
Purchase #2	$7.72	11.497%	$8.6076	$8.61	$8.60	$8.60
Purchase #3	$199.81	11.794%	$223.3756	$223.38	$223.40	$223.40
Purchase #4	$52.42	11.530%	$58.464	$58.46	$58.45	$58.50
Purchase #5	$82.93	3.635%	$85.9445	$85.94	$85.95	$85.90
Purchase #6	$221.99	9.181%	$242.3709	$242.37	$242.35	$242.40
Purchase #7	$33.83	4.817%	$35.4596	$35.46	$35.45	$35.50
7 purchase totals =	$693.65		$756.3115	$756.31	$756.30	$756.40