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	$93.63	10.361%	$103.331	$103.33	$103.35	$103.30
Purchase #2	$142.92	5.828%	$151.2494	$151.25	$151.25	$151.20
Purchase #3	$219.29	11.163%	$243.7693	$243.77	$243.75	$243.80
Purchase #4	$162.75	3.805%	$168.9426	$168.94	$168.95	$168.90
Purchase #5	$85.69	11.562%	$95.5975	$95.60	$95.60	$95.60
Purchase #6	$21.37	5.269%	$22.496	$22.50	$22.50	$22.50
Purchase #7	$91.28	9.219%	$99.6951	$99.70	$99.70	$99.70
7 purchase totals =	$816.93		$885.0809	$885.09	$885.10	$885.00