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	$105.45	11.747%	$117.8372	$117.84	$117.85	$117.80
Purchase #2	$183.35	7.240%	$196.6245	$196.62	$196.60	$196.60
Purchase #3	$231.47	13.423%	$262.5402	$262.54	$262.55	$262.50
Purchase #4	$53.87	11.476%	$60.0521	$60.05	$60.05	$60.10
Purchase #5	$216.27	13.262%	$244.9517	$244.95	$244.95	$245.00
Purchase #6	$139.50	5.251%	$146.8251	$146.83	$146.85	$146.80
Purchase #7	$53.34	7.256%	$57.2104	$57.21	$57.20	$57.20
7 purchase totals =	$983.25		$1,086.0412	$1,086.04	$1,086.05	$1,086.00