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	$100.55	10.466%	$111.0736	$111.07	$111.05	$111.10
Purchase #2	$201.72	11.544%	$225.0066	$225.01	$225.00	$225.00
Purchase #3	$156.69	6.500%	$166.8749	$166.87	$166.85	$166.90
Purchase #4	$44.44	3.466%	$45.9803	$45.98	$46.00	$46.00
Purchase #5	$22.68	3.676%	$23.5137	$23.51	$23.50	$23.50
Purchase #6	$230.71	5.280%	$242.8915	$242.89	$242.90	$242.90
Purchase #7	$225.28	3.595%	$233.3788	$233.38	$233.40	$233.40
7 purchase totals =	$982.07		$1,048.7194	$1,048.71	$1,048.70	$1,048.80