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	$214.26	3.833%	$222.4726	$222.47	$222.45	$222.50
Purchase #2	$179.63	9.351%	$196.4272	$196.43	$196.45	$196.40
Purchase #3	$170.61	13.306%	$193.3114	$193.31	$193.30	$193.30
Purchase #4	$208.31	4.383%	$217.4402	$217.44	$217.45	$217.40
Purchase #5	$51.33	4.211%	$53.4915	$53.49	$53.50	$53.50
Purchase #6	$238.93	3.645%	$247.639	$247.64	$247.65	$247.60
Purchase #7	$53.61	10.231%	$59.0948	$59.09	$59.10	$59.10
7 purchase totals =	$1,116.68		$1,189.8767	$1,189.87	$1,189.90	$1,189.80