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	$183.35	11.776%	$204.9413	$204.94	$204.95	$204.90
Purchase #2	$210.33	13.340%	$238.388	$238.39	$238.40	$238.40
Purchase #3	$79.95	6.868%	$85.441	$85.44	$85.45	$85.40
Purchase #4	$174.85	12.602%	$196.8846	$196.88	$196.90	$196.90
Purchase #5	$206.63	12.207%	$231.8533	$231.85	$231.85	$231.90
Purchase #6	$42.47	10.547%	$46.9493	$46.95	$46.95	$46.90
Purchase #7	$190.40	6.331%	$202.4542	$202.45	$202.45	$202.50
7 purchase totals =	$1,087.98		$1,206.9117	$1,206.90	$1,206.95	$1,206.90