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	$24.49	4.161%	$25.509	$25.51	$25.50	$25.50
Purchase #2	$184.87	6.108%	$196.1619	$196.16	$196.15	$196.20
Purchase #3	$56.39	4.185%	$58.7499	$58.75	$58.75	$58.70
Purchase #4	$84.99	8.513%	$92.2252	$92.23	$92.25	$92.20
Purchase #5	$98.95	3.202%	$102.1184	$102.12	$102.10	$102.10
Purchase #6	$235.55	8.630%	$255.878	$255.88	$255.90	$255.90
Purchase #7	$176.63	11.409%	$196.7817	$196.78	$196.80	$196.80
7 purchase totals =	$861.87		$927.4241	$927.43	$927.45	$927.40