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	$196.29	13.323%	$222.4417	$222.44	$222.45	$222.40
Purchase #2	$45.41	4.512%	$47.4589	$47.46	$47.45	$47.50
Purchase #3	$202.44	11.443%	$225.6052	$225.61	$225.60	$225.60
Purchase #4	$224.51	13.532%	$254.8907	$254.89	$254.90	$254.90
Purchase #5	$7.40	7.491%	$7.9543	$7.95	$7.95	$8.00
Purchase #6	$224.30	13.807%	$255.2691	$255.27	$255.25	$255.30
Purchase #7	$90.89	10.204%	$100.1644	$100.16	$100.15	$100.20
7 purchase totals =	$991.24		$1,113.7843	$1,113.78	$1,113.75	$1,113.90