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	$187.40	9.864%	$205.8851	$205.89	$205.90	$205.90
Purchase #2	$151.59	8.669%	$164.7313	$164.73	$164.75	$164.70
Purchase #3	$189.70	3.498%	$196.3357	$196.34	$196.35	$196.30
Purchase #4	$107.87	3.702%	$111.8633	$111.86	$111.85	$111.90
Purchase #5	$13.58	7.305%	$14.572	$14.57	$14.55	$14.60
Purchase #6	$14.67	3.630%	$15.2025	$15.20	$15.20	$15.20
Purchase #7	$204.28	7.623%	$219.8523	$219.85	$219.85	$219.90
7 purchase totals =	$869.09		$928.4422	$928.44	$928.45	$928.50