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	$57.45	9.874%	$63.1226	$63.12	$63.10	$63.10
Purchase #2	$191.89	11.256%	$213.4891	$213.49	$213.50	$213.50
Purchase #3	$136.93	7.374%	$147.0272	$147.03	$147.05	$147.00
Purchase #4	$119.48	3.611%	$123.7944	$123.79	$123.80	$123.80
Purchase #5	$223.84	8.345%	$242.5194	$242.52	$242.50	$242.50
Purchase #6	$140.61	9.874%	$154.4938	$154.49	$154.50	$154.50
Purchase #7	$104.87	4.496%	$109.585	$109.59	$109.60	$109.60
7 purchase totals =	$975.07		$1,054.0315	$1,054.03	$1,054.05	$1,054.00