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	$236.66	9.331%	$258.7427	$258.74	$258.75	$258.70
Purchase #2	$82.83	5.178%	$87.1189	$87.12	$87.10	$87.10
Purchase #3	$142.40	7.104%	$152.5161	$152.52	$152.50	$152.50
Purchase #4	$87.51	7.526%	$94.096	$94.10	$94.10	$94.10
Purchase #5	$90.45	13.751%	$102.8878	$102.89	$102.90	$102.90
Purchase #6	$242.99	9.863%	$266.9561	$266.96	$266.95	$267.00
Purchase #7	$47.89	9.821%	$52.5933	$52.59	$52.60	$52.60
7 purchase totals =	$930.73		$1,014.9109	$1,014.92	$1,014.90	$1,014.90