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	$89.57	3.457%	$92.6664	$92.67	$92.65	$92.70
Purchase #2	$70.45	3.465%	$72.8911	$72.89	$72.90	$72.90
Purchase #3	$134.67	7.419%	$144.6612	$144.66	$144.65	$144.70
Purchase #4	$160.60	4.700%	$168.1482	$168.15	$168.15	$168.10
Purchase #5	$12.60	7.196%	$13.5067	$13.51	$13.50	$13.50
Purchase #6	$106.58	12.416%	$119.813	$119.81	$119.80	$119.80
Purchase #7	$120.60	3.332%	$124.6184	$124.62	$124.60	$124.60
7 purchase totals =	$695.07		$736.3050	$736.31	$736.25	$736.30