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	$209.95	3.678%	$217.672	$217.67	$217.65	$217.70
Purchase #2	$35.57	5.354%	$37.4744	$37.47	$37.45	$37.50
Purchase #3	$15.96	9.479%	$17.4728	$17.47	$17.45	$17.50
Purchase #4	$105.36	7.116%	$112.8574	$112.86	$112.85	$112.90
Purchase #5	$50.38	4.223%	$52.5075	$52.51	$52.50	$52.50
Purchase #6	$190.39	4.579%	$199.108	$199.11	$199.10	$199.10
Purchase #7	$54.34	5.296%	$57.2178	$57.22	$57.20	$57.20
7 purchase totals =	$661.95		$694.3099	$694.31	$694.20	$694.40