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	$194.47	9.765%	$213.46	$213.46	$213.45	$213.50
Purchase #2	$95.62	12.544%	$107.6146	$107.61	$107.60	$107.60
Purchase #3	$144.57	12.406%	$162.5054	$162.51	$162.50	$162.50
Purchase #4	$99.42	11.656%	$111.0084	$111.01	$111.00	$111.00
Purchase #5	$159.27	3.351%	$164.6071	$164.61	$164.60	$164.60
Purchase #6	$110.77	12.789%	$124.9364	$124.94	$124.95	$124.90
Purchase #7	$64.46	8.642%	$70.0306	$70.03	$70.05	$70.00
7 purchase totals =	$868.58		$954.1625	$954.17	$954.15	$954.10