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	$43.39	6.806%	$46.3431	$46.34	$46.35	$46.30
Purchase #2	$137.52	5.765%	$145.448	$145.45	$145.45	$145.40
Purchase #3	$209.47	6.528%	$223.1442	$223.14	$223.15	$223.10
Purchase #4	$102.80	8.166%	$111.1946	$111.19	$111.20	$111.20
Purchase #5	$243.60	5.232%	$256.3452	$256.35	$256.35	$256.30
Purchase #6	$45.80	11.373%	$51.0088	$51.01	$51.00	$51.00
Purchase #7	$185.52	3.440%	$191.9019	$191.90	$191.90	$191.90
7 purchase totals =	$968.10		$1,025.3858	$1,025.38	$1,025.40	$1,025.20