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	$126.81	3.411%	$131.1355	$131.14	$131.15	$131.10
Purchase #2	$223.40	6.861%	$238.7275	$238.73	$238.75	$238.70
Purchase #3	$46.26	12.275%	$51.9384	$51.94	$51.95	$51.90
Purchase #4	$104.77	13.703%	$119.1266	$119.13	$119.15	$119.10
Purchase #5	$244.82	8.366%	$265.3016	$265.30	$265.30	$265.30
Purchase #6	$133.83	8.711%	$145.4879	$145.49	$145.50	$145.50
Purchase #7	$69.87	3.756%	$72.4943	$72.49	$72.50	$72.50
7 purchase totals =	$949.76		$1,024.2118	$1,024.22	$1,024.30	$1,024.10