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	$208.59	5.293%	$219.6307	$219.63	$219.65	$219.60
Purchase #2	$81.43	5.516%	$85.9217	$85.92	$85.90	$85.90
Purchase #3	$92.59	6.576%	$98.6787	$98.68	$98.70	$98.70
Purchase #4	$94.82	10.766%	$105.0283	$105.03	$105.05	$105.00
Purchase #5	$242.37	6.562%	$258.2743	$258.27	$258.25	$258.30
Purchase #6	$86.86	9.759%	$95.3367	$95.34	$95.35	$95.30
Purchase #7	$73.32	3.753%	$76.0717	$76.07	$76.05	$76.10
7 purchase totals =	$879.98		$938.9421	$938.94	$938.95	$938.90