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	$190.89	7.589%	$205.3766	$205.38	$205.40	$205.40
Purchase #2	$195.72	11.245%	$217.7287	$217.73	$217.75	$217.70
Purchase #3	$100.92	13.846%	$114.8934	$114.89	$114.90	$114.90
Purchase #4	$160.55	6.233%	$170.5571	$170.56	$170.55	$170.60
Purchase #5	$51.81	3.188%	$53.4617	$53.46	$53.45	$53.50
Purchase #6	$125.54	11.787%	$140.3374	$140.34	$140.35	$140.30
Purchase #7	$171.87	11.816%	$192.1782	$192.18	$192.20	$192.20
7 purchase totals =	$997.30		$1,094.5331	$1,094.54	$1,094.60	$1,094.60