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	$228.55	6.767%	$244.016	$244.02	$244.00	$244.00
Purchase #2	$5.89	7.231%	$6.3159	$6.32	$6.30	$6.30
Purchase #3	$95.98	12.577%	$108.0514	$108.05	$108.05	$108.10
Purchase #4	$209.27	6.322%	$222.5	$222.50	$222.50	$222.50
Purchase #5	$53.56	10.676%	$59.2781	$59.28	$59.30	$59.30
Purchase #6	$223.48	3.644%	$231.6236	$231.62	$231.60	$231.60
Purchase #7	$118.44	6.809%	$126.5046	$126.50	$126.50	$126.50
7 purchase totals =	$935.17		$998.2896	$998.29	$998.25	$998.30