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	$34.90	3.396%	$36.0852	$36.09	$36.10	$36.10
Purchase #2	$107.66	4.441%	$112.4412	$112.44	$112.45	$112.40
Purchase #3	$242.43	13.169%	$274.3556	$274.36	$274.35	$274.40
Purchase #4	$185.54	6.300%	$197.229	$197.23	$197.25	$197.20
Purchase #5	$241.74	6.821%	$258.2291	$258.23	$258.25	$258.20
Purchase #6	$177.78	10.549%	$196.534	$196.53	$196.55	$196.50
Purchase #7	$32.34	13.109%	$36.5795	$36.58	$36.60	$36.60
7 purchase totals =	$1,022.39		$1,111.4536	$1,111.46	$1,111.55	$1,111.40