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	$142.89	6.351%	$151.9649	$151.96	$151.95	$152.00
Purchase #2	$178.28	11.780%	$199.2814	$199.28	$199.30	$199.30
Purchase #3	$22.48	9.792%	$24.6812	$24.68	$24.70	$24.70
Purchase #4	$168.94	11.713%	$188.7279	$188.73	$188.75	$188.70
Purchase #5	$217.33	7.433%	$233.4841	$233.48	$233.50	$233.50
Purchase #6	$142.59	3.131%	$147.0545	$147.05	$147.05	$147.10
Purchase #7	$22.72	7.108%	$24.3349	$24.33	$24.35	$24.30
7 purchase totals =	$895.23		$969.5289	$969.51	$969.60	$969.60