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	$106.92	5.298%	$112.5846	$112.58	$112.60	$112.60
Purchase #2	$190.56	3.164%	$196.5893	$196.59	$196.60	$196.60
Purchase #3	$100.71	11.315%	$112.1053	$112.11	$112.10	$112.10
Purchase #4	$179.32	4.844%	$188.0063	$188.01	$188.00	$188.00
Purchase #5	$217.52	12.177%	$244.0074	$244.01	$244.00	$244.00
Purchase #6	$134.62	4.725%	$140.9808	$140.98	$141.00	$141.00
Purchase #7	$11.39	7.448%	$12.2383	$12.24	$12.25	$12.20
7 purchase totals =	$941.04		$1,006.5120	$1,006.52	$1,006.55	$1,006.50