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	$182.38	13.324%	$206.6803	$206.68	$206.70	$206.70
Purchase #2	$142.58	5.547%	$150.4889	$150.49	$150.50	$150.50
Purchase #3	$89.49	3.527%	$92.6463	$92.65	$92.65	$92.60
Purchase #4	$152.95	7.383%	$164.2423	$164.24	$164.25	$164.20
Purchase #5	$228.81	6.868%	$244.5247	$244.52	$244.50	$244.50
Purchase #6	$149.85	12.189%	$168.1152	$168.12	$168.10	$168.10
Purchase #7	$30.29	7.169%	$32.4615	$32.46	$32.45	$32.50
7 purchase totals =	$976.35		$1,059.1592	$1,059.16	$1,059.15	$1,059.10