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	$105.65	10.121%	$116.3428	$116.34	$116.35	$116.30
Purchase #2	$196.58	13.324%	$222.7723	$222.77	$222.75	$222.80
Purchase #3	$82.96	7.865%	$89.4848	$89.48	$89.50	$89.50
Purchase #4	$102.44	7.421%	$110.0421	$110.04	$110.05	$110.00
Purchase #5	$247.64	4.790%	$259.502	$259.50	$259.50	$259.50
Purchase #6	$221.34	13.463%	$251.139	$251.14	$251.15	$251.10
Purchase #7	$108.26	10.756%	$119.9044	$119.90	$119.90	$119.90
7 purchase totals =	$1,064.87		$1,169.1874	$1,169.17	$1,169.20	$1,169.10