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	$186.99	5.119%	$196.562	$196.56	$196.55	$196.60
Purchase #2	$206.87	8.501%	$224.456	$224.46	$224.45	$224.50
Purchase #3	$207.94	6.583%	$221.6287	$221.63	$221.65	$221.60
Purchase #4	$44.81	10.511%	$49.52	$49.52	$49.50	$49.50
Purchase #5	$57.51	12.182%	$64.5159	$64.52	$64.50	$64.50
Purchase #6	$248.63	6.210%	$264.0699	$264.07	$264.05	$264.10
Purchase #7	$60.72	8.220%	$65.7112	$65.71	$65.70	$65.70
7 purchase totals =	$1,013.47		$1,086.4637	$1,086.47	$1,086.40	$1,086.50