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	$137.39	10.620%	$151.9808	$151.98	$152.00	$152.00
Purchase #2	$92.72	13.292%	$105.0443	$105.04	$105.05	$105.00
Purchase #3	$247.43	10.547%	$273.5264	$273.53	$273.55	$273.50
Purchase #4	$230.99	13.224%	$261.5361	$261.54	$261.55	$261.50
Purchase #5	$118.82	4.843%	$124.5745	$124.57	$124.55	$124.60
Purchase #6	$11.79	6.264%	$12.5285	$12.53	$12.55	$12.50
Purchase #7	$241.80	4.663%	$253.0751	$253.08	$253.10	$253.10
7 purchase totals =	$1,080.94		$1,182.2657	$1,182.27	$1,182.35	$1,182.20