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	$224.64	10.628%	$248.5147	$248.51	$248.50	$248.50
Purchase #2	$81.76	13.479%	$92.7804	$92.78	$92.80	$92.80
Purchase #3	$134.92	12.817%	$152.2127	$152.21	$152.20	$152.20
Purchase #4	$96.63	9.707%	$106.0099	$106.01	$106.00	$106.00
Purchase #5	$68.67	5.395%	$72.3747	$72.37	$72.35	$72.40
Purchase #6	$86.38	4.836%	$90.5573	$90.56	$90.55	$90.60
Purchase #7	$93.98	11.871%	$105.1364	$105.14	$105.15	$105.10
7 purchase totals =	$786.98		$867.5861	$867.58	$867.55	$867.60