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	$203.27	4.440%	$212.2952	$212.30	$212.30	$212.30
Purchase #2	$14.61	5.764%	$15.4521	$15.45	$15.45	$15.50
Purchase #3	$80.82	6.699%	$86.2341	$86.23	$86.25	$86.20
Purchase #4	$246.55	12.568%	$277.5364	$277.54	$277.55	$277.50
Purchase #5	$164.72	12.663%	$185.5785	$185.58	$185.60	$185.60
Purchase #6	$20.42	5.619%	$21.5674	$21.57	$21.55	$21.60
Purchase #7	$102.94	12.553%	$115.8621	$115.86	$115.85	$115.90
7 purchase totals =	$833.33		$914.5258	$914.53	$914.55	$914.60