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	$114.62	10.416%	$126.5588	$126.56	$126.55	$126.60
Purchase #2	$185.40	10.788%	$205.401	$205.40	$205.40	$205.40
Purchase #3	$65.67	3.389%	$67.8956	$67.90	$67.90	$67.90
Purchase #4	$82.57	6.482%	$87.9222	$87.92	$87.90	$87.90
Purchase #5	$126.95	11.473%	$141.515	$141.52	$141.50	$141.50
Purchase #6	$143.54	10.403%	$158.4725	$158.47	$158.45	$158.50
Purchase #7	$174.90	4.113%	$182.0936	$182.09	$182.10	$182.10
7 purchase totals =	$893.65		$969.8587	$969.86	$969.80	$969.90