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	$214.67	4.591%	$224.5255	$224.53	$224.55	$224.50
Purchase #2	$104.84	4.699%	$109.7664	$109.77	$109.75	$109.80
Purchase #3	$67.65	5.185%	$71.1577	$71.16	$71.15	$71.20
Purchase #4	$183.35	7.258%	$196.6575	$196.66	$196.65	$196.70
Purchase #5	$191.40	12.462%	$215.2523	$215.25	$215.25	$215.30
Purchase #6	$10.72	12.422%	$12.0516	$12.05	$12.05	$12.10
Purchase #7	$241.68	10.769%	$267.7065	$267.71	$267.70	$267.70
7 purchase totals =	$1,014.31		$1,097.1175	$1,097.13	$1,097.10	$1,097.30