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	$72.82	4.568%	$76.1464	$76.15	$76.15	$76.10
Purchase #2	$67.27	3.488%	$69.6164	$69.62	$69.60	$69.60
Purchase #3	$170.91	6.746%	$182.4396	$182.44	$182.45	$182.40
Purchase #4	$174.31	6.157%	$185.0423	$185.04	$185.05	$185.00
Purchase #5	$165.97	4.271%	$173.0586	$173.06	$173.05	$173.10
Purchase #6	$108.93	5.127%	$114.5148	$114.51	$114.50	$114.50
Purchase #7	$242.69	11.833%	$271.4075	$271.41	$271.40	$271.40
7 purchase totals =	$1,002.90		$1,072.2256	$1,072.23	$1,072.20	$1,072.10