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	$206.46	3.728%	$214.1568	$214.16	$214.15	$214.20
Purchase #2	$240.25	5.252%	$252.8679	$252.87	$252.85	$252.90
Purchase #3	$167.58	9.134%	$182.8868	$182.89	$182.90	$182.90
Purchase #4	$233.88	13.540%	$265.5474	$265.55	$265.55	$265.50
Purchase #5	$152.66	13.139%	$172.718	$172.72	$172.70	$172.70
Purchase #6	$150.51	7.282%	$161.4701	$161.47	$161.45	$161.50
Purchase #7	$148.91	13.306%	$168.724	$168.72	$168.70	$168.70
7 purchase totals =	$1,300.25		$1,418.3710	$1,418.38	$1,418.30	$1,418.40