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	$95.97	6.140%	$101.8626	$101.86	$101.85	$101.90
Purchase #2	$10.60	5.667%	$11.2007	$11.20	$11.20	$11.20
Purchase #3	$36.37	10.121%	$40.051	$40.05	$40.05	$40.10
Purchase #4	$161.25	6.247%	$171.3233	$171.32	$171.30	$171.30
Purchase #5	$6.53	10.766%	$7.233	$7.23	$7.25	$7.20
Purchase #6	$242.64	8.338%	$262.8713	$262.87	$262.85	$262.90
Purchase #7	$120.75	13.727%	$137.3254	$137.33	$137.35	$137.30
7 purchase totals =	$674.11		$731.8673	$731.86	$731.85	$731.90