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	$176.50	4.700%	$184.7955	$184.80	$184.80	$184.80
Purchase #2	$11.69	4.179%	$12.1785	$12.18	$12.20	$12.20
Purchase #3	$136.66	3.785%	$141.8326	$141.83	$141.85	$141.80
Purchase #4	$87.72	5.770%	$92.7814	$92.78	$92.80	$92.80
Purchase #5	$161.90	3.843%	$168.1218	$168.12	$168.10	$168.10
Purchase #6	$112.62	5.157%	$118.4278	$118.43	$118.45	$118.40
Purchase #7	$212.40	5.331%	$223.723	$223.72	$223.70	$223.70
7 purchase totals =	$899.49		$941.8606	$941.86	$941.90	$941.80