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	$131.64	13.561%	$149.4917	$149.49	$149.50	$149.50
Purchase #2	$38.76	11.200%	$43.1011	$43.10	$43.10	$43.10
Purchase #3	$96.62	8.107%	$104.453	$104.45	$104.45	$104.50
Purchase #4	$161.45	10.433%	$178.2941	$178.29	$178.30	$178.30
Purchase #5	$125.31	5.813%	$132.5943	$132.59	$132.60	$132.60
Purchase #6	$208.31	11.856%	$233.0072	$233.01	$233.00	$233.00
Purchase #7	$245.91	11.246%	$273.565	$273.57	$273.55	$273.60
7 purchase totals =	$1,008.00		$1,114.5064	$1,114.50	$1,114.50	$1,114.60