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	$98.72	10.238%	$108.827	$108.83	$108.85	$108.80
Purchase #2	$100.99	13.771%	$114.8973	$114.90	$114.90	$114.90
Purchase #3	$114.53	12.299%	$128.616	$128.62	$128.60	$128.60
Purchase #4	$223.77	5.705%	$236.5361	$236.54	$236.55	$236.50
Purchase #5	$181.38	9.621%	$198.8306	$198.83	$198.85	$198.80
Purchase #6	$44.89	9.404%	$49.1115	$49.11	$49.10	$49.10
Purchase #7	$177.69	4.544%	$185.7642	$185.76	$185.75	$185.80
7 purchase totals =	$941.97		$1,022.5827	$1,022.59	$1,022.60	$1,022.50