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	$207.42	7.476%	$222.9267	$222.93	$222.95	$222.90
Purchase #2	$52.92	6.841%	$56.5403	$56.54	$56.55	$56.50
Purchase #3	$226.52	6.818%	$241.9641	$241.96	$241.95	$242.00
Purchase #4	$220.63	7.323%	$236.7867	$236.79	$236.80	$236.80
Purchase #5	$83.89	8.312%	$90.8629	$90.86	$90.85	$90.90
Purchase #6	$178.27	11.364%	$198.5286	$198.53	$198.55	$198.50
Purchase #7	$36.85	3.337%	$38.0797	$38.08	$38.10	$38.10
7 purchase totals =	$1,006.50		$1,085.6890	$1,085.69	$1,085.75	$1,085.70