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	$165.57	5.315%	$174.37	$174.37	$174.35	$174.40
Purchase #2	$24.25	4.330%	$25.3	$25.30	$25.30	$25.30
Purchase #3	$54.88	11.732%	$61.3185	$61.32	$61.30	$61.30
Purchase #4	$13.88	11.850%	$15.5248	$15.52	$15.50	$15.50
Purchase #5	$120.39	8.371%	$130.4678	$130.47	$130.45	$130.50
Purchase #6	$40.51	3.623%	$41.9777	$41.98	$42.00	$42.00
Purchase #7	$21.30	6.561%	$22.6975	$22.70	$22.70	$22.70
7 purchase totals =	$440.78		$471.6563	$471.66	$471.60	$471.70