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	$168.63	12.825%	$190.2568	$190.26	$190.25	$190.30
Purchase #2	$11.65	9.535%	$12.7608	$12.76	$12.75	$12.80
Purchase #3	$94.31	10.822%	$104.5162	$104.52	$104.50	$104.50
Purchase #4	$95.96	4.528%	$100.3051	$100.31	$100.30	$100.30
Purchase #5	$41.98	4.862%	$44.0211	$44.02	$44.00	$44.00
Purchase #6	$132.30	10.414%	$146.0777	$146.08	$146.10	$146.10
Purchase #7	$185.36	11.407%	$206.504	$206.50	$206.50	$206.50
7 purchase totals =	$730.19		$804.4417	$804.45	$804.40	$804.50