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	$188.55	4.238%	$196.5407	$196.54	$196.55	$196.50
Purchase #2	$226.62	3.195%	$233.8605	$233.86	$233.85	$233.90
Purchase #3	$211.67	3.228%	$218.5027	$218.50	$218.50	$218.50
Purchase #4	$47.64	8.230%	$51.5608	$51.56	$51.55	$51.60
Purchase #5	$120.57	7.557%	$129.6815	$129.68	$129.70	$129.70
Purchase #6	$156.29	11.708%	$174.5884	$174.59	$174.60	$174.60
Purchase #7	$32.47	12.368%	$36.4859	$36.49	$36.50	$36.50
7 purchase totals =	$983.81		$1,041.2205	$1,041.22	$1,041.25	$1,041.30