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	$173.45	13.303%	$196.5241	$196.52	$196.50	$196.50
Purchase #2	$48.25	12.198%	$54.1355	$54.14	$54.15	$54.10
Purchase #3	$29.29	11.382%	$32.6238	$32.62	$32.60	$32.60
Purchase #4	$198.80	3.543%	$205.8435	$205.84	$205.85	$205.80
Purchase #5	$181.58	10.631%	$200.8838	$200.88	$200.90	$200.90
Purchase #6	$137.46	3.555%	$142.3467	$142.35	$142.35	$142.30
Purchase #7	$197.38	8.802%	$214.7534	$214.75	$214.75	$214.80
7 purchase totals =	$966.21		$1,047.1108	$1,047.10	$1,047.10	$1,047.00