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	$65.95	8.162%	$71.3328	$71.33	$71.35	$71.30
Purchase #2	$24.90	7.812%	$26.8452	$26.85	$26.85	$26.80
Purchase #3	$29.41	7.841%	$31.716	$31.72	$31.70	$31.70
Purchase #4	$249.95	5.825%	$264.5096	$264.51	$264.50	$264.50
Purchase #5	$109.78	13.469%	$124.5663	$124.57	$124.55	$124.60
Purchase #6	$171.28	4.237%	$178.5371	$178.54	$178.55	$178.50
Purchase #7	$235.52	3.387%	$243.4971	$243.50	$243.50	$243.50
7 purchase totals =	$886.79		$941.0041	$941.02	$941.00	$940.90