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	$132.57	13.249%	$150.1342	$150.13	$150.15	$150.10
Purchase #2	$138.58	6.754%	$147.9397	$147.94	$147.95	$147.90
Purchase #3	$64.78	3.516%	$67.0577	$67.06	$67.05	$67.10
Purchase #4	$59.90	7.702%	$64.5135	$64.51	$64.50	$64.50
Purchase #5	$196.75	6.400%	$209.342	$209.34	$209.35	$209.30
Purchase #6	$121.78	3.107%	$125.5637	$125.56	$125.55	$125.60
Purchase #7	$98.49	13.271%	$111.5606	$111.56	$111.55	$111.60
7 purchase totals =	$812.85		$876.1114	$876.10	$876.10	$876.10