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	$130.76	9.174%	$142.7559	$142.76	$142.75	$142.80
Purchase #2	$6.38	8.607%	$6.9291	$6.93	$6.95	$6.90
Purchase #3	$108.37	4.133%	$112.8489	$112.85	$112.85	$112.80
Purchase #4	$238.28	6.816%	$254.5212	$254.52	$254.50	$254.50
Purchase #5	$127.94	13.686%	$145.4499	$145.45	$145.45	$145.40
Purchase #6	$127.33	10.614%	$140.8448	$140.84	$140.85	$140.80
Purchase #7	$250.46	4.697%	$262.2241	$262.22	$262.20	$262.20
7 purchase totals =	$989.52		$1,065.5739	$1,065.57	$1,065.55	$1,065.40