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	$169.98	7.458%	$182.6571	$182.66	$182.65	$182.70
Purchase #2	$92.65	7.227%	$99.3458	$99.35	$99.35	$99.30
Purchase #3	$217.55	3.641%	$225.471	$225.47	$225.45	$225.50
Purchase #4	$35.62	12.745%	$40.1598	$40.16	$40.15	$40.20
Purchase #5	$39.78	3.460%	$41.1564	$41.16	$41.15	$41.20
Purchase #6	$43.48	9.509%	$47.6145	$47.61	$47.60	$47.60
Purchase #7	$160.59	7.791%	$173.1016	$173.10	$173.10	$173.10
7 purchase totals =	$759.65		$809.5062	$809.51	$809.45	$809.60