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	$34.66	3.488%	$35.8689	$35.87	$35.85	$35.90
Purchase #2	$157.72	7.533%	$169.601	$169.60	$169.60	$169.60
Purchase #3	$175.61	9.771%	$192.7689	$192.77	$192.75	$192.80
Purchase #4	$182.46	9.495%	$199.7846	$199.78	$199.80	$199.80
Purchase #5	$174.91	13.674%	$198.8272	$198.83	$198.85	$198.80
Purchase #6	$147.86	13.820%	$168.2943	$168.29	$168.30	$168.30
Purchase #7	$91.95	8.810%	$100.0508	$100.05	$100.05	$100.10
7 purchase totals =	$965.17		$1,065.1957	$1,065.19	$1,065.20	$1,065.30