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	$191.52	6.561%	$204.0856	$204.09	$204.10	$204.10
Purchase #2	$249.77	5.489%	$263.4799	$263.48	$263.50	$263.50
Purchase #3	$111.64	4.669%	$116.8525	$116.85	$116.85	$116.90
Purchase #4	$145.33	3.769%	$150.8075	$150.81	$150.80	$150.80
Purchase #5	$139.52	11.457%	$155.5048	$155.50	$155.50	$155.50
Purchase #6	$153.27	7.405%	$164.6196	$164.62	$164.60	$164.60
Purchase #7	$42.53	8.618%	$46.1952	$46.20	$46.20	$46.20
7 purchase totals =	$1,033.58		$1,101.5451	$1,101.55	$1,101.55	$1,101.60