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	$206.80	7.108%	$221.4993	$221.50	$221.50	$221.50
Purchase #2	$232.91	4.162%	$242.6037	$242.60	$242.60	$242.60
Purchase #3	$20.52	6.227%	$21.7978	$21.80	$21.80	$21.80
Purchase #4	$154.78	8.604%	$168.0973	$168.10	$168.10	$168.10
Purchase #5	$54.75	13.230%	$61.9934	$61.99	$62.00	$62.00
Purchase #6	$243.72	8.531%	$264.5118	$264.51	$264.50	$264.50
Purchase #7	$99.93	13.842%	$113.7623	$113.76	$113.75	$113.80
7 purchase totals =	$1,013.41		$1,094.2656	$1,094.26	$1,094.25	$1,094.30