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	$196.62	10.705%	$217.6682	$217.67	$217.65	$217.70
Purchase #2	$98.95	12.657%	$111.4741	$111.47	$111.45	$111.50
Purchase #3	$181.96	8.456%	$197.3465	$197.35	$197.35	$197.30
Purchase #4	$160.54	5.106%	$168.7372	$168.74	$168.75	$168.70
Purchase #5	$245.38	11.213%	$272.8945	$272.89	$272.90	$272.90
Purchase #6	$118.25	4.847%	$123.9816	$123.98	$124.00	$124.00
Purchase #7	$37.63	5.738%	$39.7892	$39.79	$39.80	$39.80
7 purchase totals =	$1,039.33		$1,131.8913	$1,131.89	$1,131.90	$1,131.90