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	$56.73	5.242%	$59.7038	$59.70	$59.70	$59.70
Purchase #2	$50.30	5.317%	$52.9745	$52.97	$52.95	$53.00
Purchase #3	$27.35	5.205%	$28.7736	$28.77	$28.75	$28.80
Purchase #4	$103.67	12.649%	$116.7832	$116.78	$116.80	$116.80
Purchase #5	$240.85	6.283%	$255.9826	$255.98	$256.00	$256.00
Purchase #6	$92.71	7.438%	$99.6058	$99.61	$99.60	$99.60
Purchase #7	$132.88	13.873%	$151.3144	$151.31	$151.30	$151.30
7 purchase totals =	$704.49		$765.1379	$765.12	$765.10	$765.20