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	$217.96	5.383%	$229.6928	$229.69	$229.70	$229.70
Purchase #2	$36.40	6.500%	$38.766	$38.77	$38.75	$38.80
Purchase #3	$95.78	10.520%	$105.8561	$105.86	$105.85	$105.90
Purchase #4	$230.29	3.513%	$238.3801	$238.38	$238.40	$238.40
Purchase #5	$101.34	9.545%	$111.0129	$111.01	$111.00	$111.00
Purchase #6	$221.27	6.856%	$236.4403	$236.44	$236.45	$236.40
Purchase #7	$58.96	3.833%	$61.2199	$61.22	$61.20	$61.20
7 purchase totals =	$962.00		$1,021.3681	$1,021.37	$1,021.35	$1,021.40