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	$76.90	7.188%	$82.4276	$82.43	$82.45	$82.40
Purchase #2	$8.36	7.268%	$8.9676	$8.97	$8.95	$9.00
Purchase #3	$116.94	5.417%	$123.2746	$123.27	$123.25	$123.30
Purchase #4	$126.41	8.281%	$136.878	$136.88	$136.90	$136.90
Purchase #5	$183.92	5.186%	$193.4581	$193.46	$193.45	$193.50
Purchase #6	$59.25	5.496%	$62.5064	$62.51	$62.50	$62.50
Purchase #7	$189.50	5.801%	$200.4929	$200.49	$200.50	$200.50
7 purchase totals =	$761.28		$808.0052	$808.01	$808.00	$808.10