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	$211.45	7.775%	$227.8902	$227.89	$227.90	$227.90
Purchase #2	$117.77	3.120%	$121.4444	$121.44	$121.45	$121.40
Purchase #3	$161.37	11.219%	$179.4741	$179.47	$179.45	$179.50
Purchase #4	$69.27	3.308%	$71.5615	$71.56	$71.55	$71.60
Purchase #5	$87.50	12.625%	$98.5469	$98.55	$98.55	$98.50
Purchase #6	$184.75	3.249%	$190.7525	$190.75	$190.75	$190.80
Purchase #7	$173.89	6.356%	$184.9424	$184.94	$184.95	$184.90
7 purchase totals =	$1,006.00		$1,074.6120	$1,074.60	$1,074.60	$1,074.60