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	$118.44	7.259%	$127.0376	$127.04	$127.05	$127.00
Purchase #2	$105.50	5.537%	$111.3415	$111.34	$111.35	$111.30
Purchase #3	$143.36	5.226%	$150.852	$150.85	$150.85	$150.90
Purchase #4	$71.77	12.602%	$80.8145	$80.81	$80.80	$80.80
Purchase #5	$81.51	4.781%	$85.407	$85.41	$85.40	$85.40
Purchase #6	$246.25	8.733%	$267.755	$267.76	$267.75	$267.80
Purchase #7	$205.34	12.873%	$231.7734	$231.77	$231.75	$231.80
7 purchase totals =	$972.17		$1,054.9810	$1,054.98	$1,054.95	$1,055.00