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	$184.80	4.181%	$192.5265	$192.53	$192.55	$192.50
Purchase #2	$74.40	11.372%	$82.8608	$82.86	$82.85	$82.90
Purchase #3	$168.77	13.117%	$190.9076	$190.91	$190.90	$190.90
Purchase #4	$153.83	12.803%	$173.5249	$173.52	$173.50	$173.50
Purchase #5	$48.81	7.434%	$52.4385	$52.44	$52.45	$52.40
Purchase #6	$231.71	10.770%	$256.6652	$256.67	$256.65	$256.70
Purchase #7	$57.29	7.214%	$61.4229	$61.42	$61.40	$61.40
7 purchase totals =	$919.61		$1,010.3464	$1,010.35	$1,010.30	$1,010.30