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	$184.29	6.762%	$196.7517	$196.75	$196.75	$196.80
Purchase #2	$184.33	11.808%	$206.0957	$206.10	$206.10	$206.10
Purchase #3	$176.26	13.861%	$200.6914	$200.69	$200.70	$200.70
Purchase #4	$240.58	9.357%	$263.0911	$263.09	$263.10	$263.10
Purchase #5	$191.59	7.368%	$205.7064	$205.71	$205.70	$205.70
Purchase #6	$53.89	4.791%	$56.4719	$56.47	$56.45	$56.50
Purchase #7	$97.40	7.633%	$104.8345	$104.83	$104.85	$104.80
7 purchase totals =	$1,128.34		$1,233.6427	$1,233.64	$1,233.65	$1,233.70