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	$171.46	13.670%	$194.8986	$194.90	$194.90	$194.90
Purchase #2	$24.75	12.492%	$27.8418	$27.84	$27.85	$27.80
Purchase #3	$142.49	7.419%	$153.0613	$153.06	$153.05	$153.10
Purchase #4	$88.42	7.841%	$95.353	$95.35	$95.35	$95.40
Purchase #5	$199.53	10.710%	$220.8997	$220.90	$220.90	$220.90
Purchase #6	$152.37	13.176%	$172.4463	$172.45	$172.45	$172.40
Purchase #7	$186.71	5.749%	$197.444	$197.44	$197.45	$197.40
7 purchase totals =	$965.73		$1,061.9447	$1,061.94	$1,061.95	$1,061.90