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	$207.27	7.438%	$222.6867	$222.69	$222.70	$222.70
Purchase #2	$124.75	4.217%	$130.0107	$130.01	$130.00	$130.00
Purchase #3	$109.48	12.851%	$123.5493	$123.55	$123.55	$123.50
Purchase #4	$22.92	11.609%	$25.5808	$25.58	$25.60	$25.60
Purchase #5	$245.30	13.433%	$278.2511	$278.25	$278.25	$278.30
Purchase #6	$73.43	12.516%	$82.6205	$82.62	$82.60	$82.60
Purchase #7	$138.72	4.856%	$145.4562	$145.46	$145.45	$145.50
7 purchase totals =	$921.87		$1,008.1553	$1,008.16	$1,008.15	$1,008.20