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	$206.68	4.203%	$215.3668	$215.37	$215.35	$215.40
Purchase #2	$167.43	5.412%	$176.4913	$176.49	$176.50	$176.50
Purchase #3	$67.71	7.738%	$72.9494	$72.95	$72.95	$72.90
Purchase #4	$104.41	9.651%	$114.4866	$114.49	$114.50	$114.50
Purchase #5	$111.70	13.842%	$127.1615	$127.16	$127.15	$127.20
Purchase #6	$225.94	3.144%	$233.0436	$233.04	$233.05	$233.00
Purchase #7	$106.67	8.682%	$115.9311	$115.93	$115.95	$115.90
7 purchase totals =	$990.54		$1,055.4303	$1,055.43	$1,055.45	$1,055.40