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	$179.46	9.108%	$195.8052	$195.81	$195.80	$195.80
Purchase #2	$158.40	13.688%	$180.0818	$180.08	$180.10	$180.10
Purchase #3	$102.50	6.502%	$109.1646	$109.16	$109.15	$109.20
Purchase #4	$102.83	8.315%	$111.3803	$111.38	$111.40	$111.40
Purchase #5	$116.48	3.115%	$120.1084	$120.11	$120.10	$120.10
Purchase #6	$144.26	7.869%	$155.6118	$155.61	$155.60	$155.60
Purchase #7	$147.78	4.530%	$154.4744	$154.47	$154.45	$154.50
7 purchase totals =	$951.71		$1,026.6265	$1,026.62	$1,026.60	$1,026.70