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	$222.81	7.107%	$238.6451	$238.65	$238.65	$238.60
Purchase #2	$91.83	10.809%	$101.7559	$101.76	$101.75	$101.80
Purchase #3	$37.26	7.162%	$39.9286	$39.93	$39.95	$39.90
Purchase #4	$139.80	9.800%	$153.5004	$153.50	$153.50	$153.50
Purchase #5	$70.64	11.638%	$78.8611	$78.86	$78.85	$78.90
Purchase #6	$56.42	5.475%	$59.509	$59.51	$59.50	$59.50
Purchase #7	$226.50	8.665%	$246.1262	$246.13	$246.15	$246.10
7 purchase totals =	$845.26		$918.3263	$918.34	$918.35	$918.30