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	$188.42	3.454%	$194.928	$194.93	$194.95	$194.90
Purchase #2	$87.86	3.102%	$90.5854	$90.59	$90.60	$90.60
Purchase #3	$238.60	4.619%	$249.6209	$249.62	$249.60	$249.60
Purchase #4	$109.88	13.233%	$124.4204	$124.42	$124.40	$124.40
Purchase #5	$192.65	9.867%	$211.6588	$211.66	$211.65	$211.70
Purchase #6	$109.76	12.116%	$123.0585	$123.06	$123.05	$123.10
Purchase #7	$125.96	12.389%	$141.5652	$141.57	$141.55	$141.60
7 purchase totals =	$1,053.13		$1,135.8372	$1,135.85	$1,135.80	$1,135.90