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	$116.44	9.844%	$127.9024	$127.90	$127.90	$127.90
Purchase #2	$5.48	6.310%	$5.8258	$5.83	$5.85	$5.80
Purchase #3	$128.90	4.181%	$134.2893	$134.29	$134.30	$134.30
Purchase #4	$137.90	9.461%	$150.9467	$150.95	$150.95	$150.90
Purchase #5	$174.83	8.522%	$189.729	$189.73	$189.75	$189.70
Purchase #6	$237.54	5.313%	$250.1605	$250.16	$250.15	$250.20
Purchase #7	$200.98	7.814%	$216.6846	$216.68	$216.70	$216.70
7 purchase totals =	$1,002.07		$1,075.5383	$1,075.54	$1,075.60	$1,075.50