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	$131.42	7.426%	$141.1792	$141.18	$141.20	$141.20
Purchase #2	$142.54	11.242%	$158.5643	$158.56	$158.55	$158.60
Purchase #3	$179.85	6.786%	$192.0546	$192.05	$192.05	$192.10
Purchase #4	$86.99	9.872%	$95.5777	$95.58	$95.60	$95.60
Purchase #5	$233.33	9.436%	$255.347	$255.35	$255.35	$255.30
Purchase #6	$32.61	11.306%	$36.2969	$36.30	$36.30	$36.30
Purchase #7	$138.87	5.368%	$146.3245	$146.32	$146.30	$146.30
7 purchase totals =	$945.61		$1,025.3442	$1,025.34	$1,025.35	$1,025.40