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	$217.48	9.834%	$238.867	$238.87	$238.85	$238.90
Purchase #2	$53.99	4.404%	$56.3677	$56.37	$56.35	$56.40
Purchase #3	$63.96	3.838%	$66.4148	$66.41	$66.40	$66.40
Purchase #4	$73.90	6.405%	$78.6333	$78.63	$78.65	$78.60
Purchase #5	$130.75	6.377%	$139.0879	$139.09	$139.10	$139.10
Purchase #6	$239.77	12.243%	$269.125	$269.13	$269.15	$269.10
Purchase #7	$150.79	8.788%	$164.0414	$164.04	$164.05	$164.00
7 purchase totals =	$930.64		$1,012.5371	$1,012.54	$1,012.55	$1,012.50