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	$231.40	10.527%	$255.7595	$255.76	$255.75	$255.80
Purchase #2	$25.78	6.663%	$27.4977	$27.50	$27.50	$27.50
Purchase #3	$200.48	4.693%	$209.8885	$209.89	$209.90	$209.90
Purchase #4	$40.83	13.699%	$46.4233	$46.42	$46.40	$46.40
Purchase #5	$146.99	9.709%	$161.2613	$161.26	$161.25	$161.30
Purchase #6	$164.29	5.851%	$173.9026	$173.90	$173.90	$173.90
Purchase #7	$143.74	9.805%	$157.8337	$157.83	$157.85	$157.80
7 purchase totals =	$953.51		$1,032.5666	$1,032.56	$1,032.55	$1,032.60