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	$97.56	4.711%	$102.1561	$102.16	$102.15	$102.20
Purchase #2	$11.75	5.335%	$12.3769	$12.38	$12.40	$12.40
Purchase #3	$43.88	3.741%	$45.5216	$45.52	$45.50	$45.50
Purchase #4	$32.85	13.833%	$37.3941	$37.39	$37.40	$37.40
Purchase #5	$32.26	13.702%	$36.6803	$36.68	$36.70	$36.70
Purchase #6	$41.83	10.523%	$46.2318	$46.23	$46.25	$46.20
Purchase #7	$94.31	7.710%	$101.5813	$101.58	$101.60	$101.60
7 purchase totals =	$354.44		$381.9421	$381.94	$382.00	$382.00