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	$172.55	13.432%	$195.7269	$195.73	$195.75	$195.70
Purchase #2	$151.50	3.269%	$156.4525	$156.45	$156.45	$156.50
Purchase #3	$127.51	4.535%	$133.2926	$133.29	$133.30	$133.30
Purchase #4	$190.32	3.471%	$196.926	$196.93	$196.95	$196.90
Purchase #5	$92.85	5.257%	$97.7311	$97.73	$97.75	$97.70
Purchase #6	$77.59	7.146%	$83.1346	$83.13	$83.15	$83.10
Purchase #7	$234.87	9.129%	$256.3113	$256.31	$256.30	$256.30
7 purchase totals =	$1,047.19		$1,119.5750	$1,119.57	$1,119.65	$1,119.50