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	$12.69	12.851%	$14.3208	$14.32	$14.30	$14.30
Purchase #2	$214.88	12.186%	$241.0653	$241.07	$241.05	$241.10
Purchase #3	$233.50	13.296%	$264.5462	$264.55	$264.55	$264.50
Purchase #4	$190.34	5.474%	$200.7592	$200.76	$200.75	$200.80
Purchase #5	$72.52	3.553%	$75.0966	$75.10	$75.10	$75.10
Purchase #6	$145.41	7.323%	$156.0584	$156.06	$156.05	$156.10
Purchase #7	$95.62	4.658%	$100.074	$100.07	$100.05	$100.10
7 purchase totals =	$964.96		$1,051.9205	$1,051.93	$1,051.85	$1,052.00