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	$230.52	13.716%	$262.1381	$262.14	$262.15	$262.10
Purchase #2	$226.72	12.610%	$255.3094	$255.31	$255.30	$255.30
Purchase #3	$225.67	13.321%	$255.7315	$255.73	$255.75	$255.70
Purchase #4	$213.55	11.827%	$238.8066	$238.81	$238.80	$238.80
Purchase #5	$81.27	11.559%	$90.664	$90.66	$90.65	$90.70
Purchase #6	$215.40	5.859%	$228.0203	$228.02	$228.00	$228.00
Purchase #7	$142.51	10.619%	$157.6431	$157.64	$157.65	$157.60
7 purchase totals =	$1,335.64		$1,488.3130	$1,488.31	$1,488.30	$1,488.20