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	$108.27	3.173%	$111.7054	$111.71	$111.70	$111.70
Purchase #2	$103.32	11.331%	$115.0272	$115.03	$115.05	$115.00
Purchase #3	$46.38	3.145%	$47.8387	$47.84	$47.85	$47.80
Purchase #4	$240.58	9.195%	$262.7013	$262.70	$262.70	$262.70
Purchase #5	$201.60	11.871%	$225.5319	$225.53	$225.55	$225.50
Purchase #6	$172.44	13.741%	$196.135	$196.14	$196.15	$196.10
Purchase #7	$103.32	13.317%	$117.0791	$117.08	$117.10	$117.10
7 purchase totals =	$975.91		$1,076.0186	$1,076.03	$1,076.10	$1,075.90