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	$51.66	3.408%	$53.4206	$53.42	$53.40	$53.40
Purchase #2	$236.83	4.441%	$247.3476	$247.35	$247.35	$247.30
Purchase #3	$130.75	10.690%	$144.7272	$144.73	$144.75	$144.70
Purchase #4	$127.85	13.691%	$145.3539	$145.35	$145.35	$145.40
Purchase #5	$131.73	4.707%	$137.9305	$137.93	$137.95	$137.90
Purchase #6	$65.87	8.222%	$71.2858	$71.29	$71.30	$71.30
Purchase #7	$205.94	9.449%	$225.3993	$225.40	$225.40	$225.40
7 purchase totals =	$950.63		$1,025.4649	$1,025.47	$1,025.50	$1,025.40