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	$93.26	3.471%	$96.4971	$96.50	$96.50	$96.50
Purchase #2	$120.26	5.407%	$126.7625	$126.76	$126.75	$126.80
Purchase #3	$28.58	12.204%	$32.0679	$32.07	$32.05	$32.10
Purchase #4	$64.70	12.206%	$72.5973	$72.60	$72.60	$72.60
Purchase #5	$40.89	4.127%	$42.5775	$42.58	$42.60	$42.60
Purchase #6	$130.27	11.757%	$145.5858	$145.59	$145.60	$145.60
Purchase #7	$181.81	6.241%	$193.1568	$193.16	$193.15	$193.20
7 purchase totals =	$659.77		$709.2449	$709.26	$709.25	$709.40