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	$196.33	13.515%	$222.864	$222.86	$222.85	$222.90
Purchase #2	$11.63	6.375%	$12.3714	$12.37	$12.35	$12.40
Purchase #3	$76.85	4.302%	$80.1561	$80.16	$80.15	$80.20
Purchase #4	$248.69	8.144%	$268.9433	$268.94	$268.95	$268.90
Purchase #5	$95.76	3.371%	$98.9881	$98.99	$99.00	$99.00
Purchase #6	$5.80	13.561%	$6.5865	$6.59	$6.60	$6.60
Purchase #7	$116.86	13.491%	$132.6256	$132.63	$132.65	$132.60
7 purchase totals =	$751.92		$822.5350	$822.54	$822.55	$822.60