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	$196.56	12.246%	$220.6307	$220.63	$220.65	$220.60
Purchase #2	$13.94	7.691%	$15.0121	$15.01	$15.00	$15.00
Purchase #3	$177.89	5.352%	$187.4107	$187.41	$187.40	$187.40
Purchase #4	$218.31	13.573%	$247.9412	$247.94	$247.95	$247.90
Purchase #5	$217.46	9.715%	$238.5862	$238.59	$238.60	$238.60
Purchase #6	$11.53	10.389%	$12.7279	$12.73	$12.75	$12.70
Purchase #7	$188.59	4.300%	$196.6994	$196.70	$196.70	$196.70
7 purchase totals =	$1,024.28		$1,119.0082	$1,119.01	$1,119.05	$1,118.90