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	$76.71	7.721%	$82.6328	$82.63	$82.65	$82.60
Purchase #2	$44.94	13.223%	$50.8824	$50.88	$50.90	$50.90
Purchase #3	$45.27	7.147%	$48.5054	$48.51	$48.50	$48.50
Purchase #4	$175.47	4.415%	$183.217	$183.22	$183.20	$183.20
Purchase #5	$164.32	5.680%	$173.6534	$173.65	$173.65	$173.70
Purchase #6	$115.96	3.392%	$119.8934	$119.89	$119.90	$119.90
Purchase #7	$191.88	9.775%	$210.6363	$210.64	$210.65	$210.60
7 purchase totals =	$814.55		$869.4207	$869.42	$869.45	$869.40