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	$195.56	5.452%	$206.2219	$206.22	$206.20	$206.20
Purchase #2	$183.81	4.223%	$191.5723	$191.57	$191.55	$191.60
Purchase #3	$215.68	13.514%	$244.827	$244.83	$244.85	$244.80
Purchase #4	$81.90	10.452%	$90.4602	$90.46	$90.45	$90.50
Purchase #5	$234.48	13.177%	$265.3774	$265.38	$265.40	$265.40
Purchase #6	$157.33	6.451%	$167.4794	$167.48	$167.50	$167.50
Purchase #7	$215.55	4.772%	$225.836	$225.84	$225.85	$225.80
7 purchase totals =	$1,284.31		$1,391.7742	$1,391.78	$1,391.80	$1,391.80