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	$179.64	11.571%	$200.4261	$200.43	$200.45	$200.40
Purchase #2	$87.59	9.509%	$95.9189	$95.92	$95.90	$95.90
Purchase #3	$226.81	8.376%	$245.8076	$245.81	$245.80	$245.80
Purchase #4	$152.72	10.626%	$168.948	$168.95	$168.95	$168.90
Purchase #5	$110.37	9.435%	$120.7834	$120.78	$120.80	$120.80
Purchase #6	$219.47	6.865%	$234.5366	$234.54	$234.55	$234.50
Purchase #7	$176.78	7.366%	$189.8016	$189.80	$189.80	$189.80
7 purchase totals =	$1,153.38		$1,256.2222	$1,256.23	$1,256.25	$1,256.10