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	$202.60	7.311%	$217.4121	$217.41	$217.40	$217.40
Purchase #2	$22.77	4.137%	$23.712	$23.71	$23.70	$23.70
Purchase #3	$155.97	10.850%	$172.8927	$172.89	$172.90	$172.90
Purchase #4	$232.69	5.202%	$244.7945	$244.79	$244.80	$244.80
Purchase #5	$181.46	5.727%	$191.8522	$191.85	$191.85	$191.90
Purchase #6	$182.69	4.314%	$190.5712	$190.57	$190.55	$190.60
Purchase #7	$41.54	4.534%	$43.4234	$43.42	$43.40	$43.40
7 purchase totals =	$1,019.72		$1,084.6581	$1,084.64	$1,084.60	$1,084.70