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	$39.75	11.663%	$44.386	$44.39	$44.40	$44.40
Purchase #2	$198.84	11.175%	$221.0604	$221.06	$221.05	$221.10
Purchase #3	$208.38	6.555%	$222.0393	$222.04	$222.05	$222.00
Purchase #4	$209.89	13.132%	$237.4528	$237.45	$237.45	$237.50
Purchase #5	$206.95	12.436%	$232.6863	$232.69	$232.70	$232.70
Purchase #6	$207.42	7.242%	$222.4414	$222.44	$222.45	$222.40
Purchase #7	$182.71	7.567%	$196.5357	$196.54	$196.55	$196.50
7 purchase totals =	$1,253.94		$1,376.6019	$1,376.61	$1,376.65	$1,376.60