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	$115.59	7.220%	$123.9356	$123.94	$123.95	$123.90
Purchase #2	$135.89	11.146%	$151.0363	$151.04	$151.05	$151.00
Purchase #3	$5.72	6.520%	$6.0929	$6.09	$6.10	$6.10
Purchase #4	$206.34	5.714%	$218.1303	$218.13	$218.15	$218.10
Purchase #5	$212.91	7.680%	$229.2615	$229.26	$229.25	$229.30
Purchase #6	$190.32	5.254%	$200.3194	$200.32	$200.30	$200.30
Purchase #7	$34.37	12.456%	$38.6511	$38.65	$38.65	$38.70
7 purchase totals =	$901.14		$967.4271	$967.43	$967.45	$967.40