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	$142.88	6.839%	$152.6516	$152.65	$152.65	$152.70
Purchase #2	$87.41	9.129%	$95.3897	$95.39	$95.40	$95.40
Purchase #3	$8.25	4.479%	$8.6195	$8.62	$8.60	$8.60
Purchase #4	$57.62	3.201%	$59.4644	$59.46	$59.45	$59.50
Purchase #5	$164.48	10.789%	$182.2257	$182.23	$182.25	$182.20
Purchase #6	$143.28	5.363%	$150.9641	$150.96	$150.95	$151.00
Purchase #7	$86.42	5.391%	$91.0789	$91.08	$91.10	$91.10
7 purchase totals =	$690.34		$740.3939	$740.39	$740.40	$740.50