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	$43.29	8.145%	$46.816	$46.82	$46.80	$46.80
Purchase #2	$119.41	6.454%	$127.1167	$127.12	$127.10	$127.10
Purchase #3	$240.35	6.553%	$256.1001	$256.10	$256.10	$256.10
Purchase #4	$14.59	8.214%	$15.7884	$15.79	$15.80	$15.80
Purchase #5	$136.32	9.612%	$149.4231	$149.42	$149.40	$149.40
Purchase #6	$248.35	5.774%	$262.6897	$262.69	$262.70	$262.70
Purchase #7	$203.72	9.263%	$222.5906	$222.59	$222.60	$222.60
7 purchase totals =	$1,006.03		$1,080.5246	$1,080.53	$1,080.50	$1,080.50