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	$52.62	12.179%	$59.0286	$59.03	$59.05	$59.00
Purchase #2	$206.32	6.702%	$220.1476	$220.15	$220.15	$220.10
Purchase #3	$137.31	12.605%	$154.6179	$154.62	$154.60	$154.60
Purchase #4	$209.95	9.633%	$230.1745	$230.17	$230.15	$230.20
Purchase #5	$36.70	10.754%	$40.6467	$40.65	$40.65	$40.60
Purchase #6	$87.93	12.676%	$99.076	$99.08	$99.10	$99.10
Purchase #7	$208.42	6.244%	$221.4337	$221.43	$221.45	$221.40
7 purchase totals =	$939.25		$1,025.1250	$1,025.13	$1,025.15	$1,025.00