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	$119.61	10.549%	$132.2277	$132.23	$132.25	$132.20
Purchase #2	$168.85	9.119%	$184.2474	$184.25	$184.25	$184.20
Purchase #3	$118.43	4.238%	$123.4491	$123.45	$123.45	$123.40
Purchase #4	$208.25	7.524%	$223.9187	$223.92	$223.90	$223.90
Purchase #5	$46.39	9.255%	$50.6834	$50.68	$50.70	$50.70
Purchase #6	$106.99	6.609%	$114.061	$114.06	$114.05	$114.10
Purchase #7	$241.51	12.578%	$271.8871	$271.89	$271.90	$271.90
7 purchase totals =	$1,010.03		$1,100.4744	$1,100.48	$1,100.50	$1,100.40