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	$108.35	5.183%	$113.9658	$113.97	$113.95	$114.00
Purchase #2	$164.28	13.170%	$185.9157	$185.92	$185.90	$185.90
Purchase #3	$27.88	13.439%	$31.6268	$31.63	$31.65	$31.60
Purchase #4	$77.67	11.192%	$86.3628	$86.36	$86.35	$86.40
Purchase #5	$81.95	5.574%	$86.5179	$86.52	$86.50	$86.50
Purchase #6	$71.76	9.333%	$78.4574	$78.46	$78.45	$78.50
Purchase #7	$128.97	3.173%	$133.0622	$133.06	$133.05	$133.10
7 purchase totals =	$660.86		$715.9086	$715.92	$715.85	$716.00