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	$55.50	10.698%	$61.4374	$61.44	$61.45	$61.40
Purchase #2	$184.70	6.344%	$196.4174	$196.42	$196.40	$196.40
Purchase #3	$221.41	12.315%	$248.6766	$248.68	$248.70	$248.70
Purchase #4	$147.83	11.496%	$164.8245	$164.82	$164.80	$164.80
Purchase #5	$81.53	8.217%	$88.2293	$88.23	$88.25	$88.20
Purchase #6	$203.53	13.644%	$231.2996	$231.30	$231.30	$231.30
Purchase #7	$97.57	8.264%	$105.6332	$105.63	$105.65	$105.60
7 purchase totals =	$992.07		$1,096.5180	$1,096.52	$1,096.55	$1,096.40