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	$85.56	10.859%	$94.851	$94.85	$94.85	$94.90
Purchase #2	$58.57	11.829%	$65.4982	$65.50	$65.50	$65.50
Purchase #3	$32.78	11.412%	$36.5209	$36.52	$36.50	$36.50
Purchase #4	$157.34	9.600%	$172.4446	$172.44	$172.45	$172.40
Purchase #5	$112.40	10.157%	$123.8165	$123.82	$123.80	$123.80
Purchase #6	$208.53	7.309%	$223.7715	$223.77	$223.75	$223.80
Purchase #7	$73.79	5.162%	$77.599	$77.60	$77.60	$77.60
7 purchase totals =	$728.97		$794.5017	$794.50	$794.45	$794.50