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	$216.50	9.249%	$236.5241	$236.52	$236.50	$236.50
Purchase #2	$42.56	10.498%	$47.0279	$47.03	$47.05	$47.00
Purchase #3	$77.99	9.849%	$85.6712	$85.67	$85.65	$85.70
Purchase #4	$221.53	6.228%	$235.3269	$235.33	$235.35	$235.30
Purchase #5	$236.61	8.540%	$256.8165	$256.82	$256.80	$256.80
Purchase #6	$74.29	5.738%	$78.5528	$78.55	$78.55	$78.60
Purchase #7	$81.82	4.239%	$85.2883	$85.29	$85.30	$85.30
7 purchase totals =	$951.30		$1,025.2077	$1,025.21	$1,025.20	$1,025.20