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	$196.42	4.707%	$205.6655	$205.67	$205.65	$205.70
Purchase #2	$229.76	13.402%	$260.5524	$260.55	$260.55	$260.60
Purchase #3	$174.89	10.137%	$192.6186	$192.62	$192.60	$192.60
Purchase #4	$41.45	10.589%	$45.8391	$45.84	$45.85	$45.80
Purchase #5	$34.83	5.735%	$36.8275	$36.83	$36.85	$36.80
Purchase #6	$163.53	4.819%	$171.4105	$171.41	$171.40	$171.40
Purchase #7	$106.76	6.417%	$113.6108	$113.61	$113.60	$113.60
7 purchase totals =	$947.64		$1,026.5244	$1,026.53	$1,026.50	$1,026.50