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	$84.67	12.190%	$94.9913	$94.99	$95.00	$95.00
Purchase #2	$51.93	5.197%	$54.6288	$54.63	$54.65	$54.60
Purchase #3	$154.91	3.618%	$160.5146	$160.51	$160.50	$160.50
Purchase #4	$38.36	11.635%	$42.8232	$42.82	$42.80	$42.80
Purchase #5	$130.78	8.342%	$141.6897	$141.69	$141.70	$141.70
Purchase #6	$39.44	10.732%	$43.6727	$43.67	$43.65	$43.70
Purchase #7	$88.71	6.543%	$94.5143	$94.51	$94.50	$94.50
7 purchase totals =	$588.80		$632.8346	$632.82	$632.80	$632.80