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	$230.89	13.568%	$262.2172	$262.22	$262.20	$262.20
Purchase #2	$73.55	6.870%	$78.6029	$78.60	$78.60	$78.60
Purchase #3	$186.35	3.470%	$192.8163	$192.82	$192.80	$192.80
Purchase #4	$128.82	3.685%	$133.567	$133.57	$133.55	$133.60
Purchase #5	$159.43	9.142%	$174.0051	$174.01	$174.00	$174.00
Purchase #6	$30.36	5.337%	$31.9803	$31.98	$32.00	$32.00
Purchase #7	$196.84	7.645%	$211.8884	$211.89	$211.90	$211.90
7 purchase totals =	$1,006.24		$1,085.0772	$1,085.09	$1,085.05	$1,085.10