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	$210.36	8.716%	$228.695	$228.70	$228.70	$228.70
Purchase #2	$38.49	10.128%	$42.3883	$42.39	$42.40	$42.40
Purchase #3	$206.29	4.489%	$215.5504	$215.55	$215.55	$215.60
Purchase #4	$54.94	8.323%	$59.5127	$59.51	$59.50	$59.50
Purchase #5	$47.38	5.381%	$49.9295	$49.93	$49.95	$49.90
Purchase #6	$185.96	10.440%	$205.3742	$205.37	$205.35	$205.40
Purchase #7	$203.72	4.288%	$212.4555	$212.46	$212.45	$212.50
7 purchase totals =	$947.14		$1,013.9056	$1,013.91	$1,013.90	$1,014.00