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	$57.43	9.290%	$62.7652	$62.77	$62.75	$62.80
Purchase #2	$88.37	8.478%	$95.862	$95.86	$95.85	$95.90
Purchase #3	$174.28	10.660%	$192.8582	$192.86	$192.85	$192.90
Purchase #4	$217.53	13.774%	$247.4926	$247.49	$247.50	$247.50
Purchase #5	$231.54	4.856%	$242.7836	$242.78	$242.80	$242.80
Purchase #6	$131.86	7.602%	$141.884	$141.88	$141.90	$141.90
Purchase #7	$154.84	6.615%	$165.0827	$165.08	$165.10	$165.10
7 purchase totals =	$1,055.85		$1,148.7283	$1,148.72	$1,148.75	$1,148.90