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	$188.73	6.435%	$200.8748	$200.87	$200.85	$200.90
Purchase #2	$201.30	5.511%	$212.3936	$212.39	$212.40	$212.40
Purchase #3	$33.68	5.373%	$35.4896	$35.49	$35.50	$35.50
Purchase #4	$114.57	4.155%	$119.3304	$119.33	$119.35	$119.30
Purchase #5	$34.56	8.112%	$37.3635	$37.36	$37.35	$37.40
Purchase #6	$118.71	10.861%	$131.6031	$131.60	$131.60	$131.60
Purchase #7	$214.26	5.103%	$225.1937	$225.19	$225.20	$225.20
7 purchase totals =	$905.81		$962.2487	$962.23	$962.25	$962.30