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	$148.73	10.431%	$164.244	$164.24	$164.25	$164.20
Purchase #2	$19.84	7.772%	$21.382	$21.38	$21.40	$21.40
Purchase #3	$196.28	13.698%	$223.1664	$223.17	$223.15	$223.20
Purchase #4	$202.38	7.789%	$218.1434	$218.14	$218.15	$218.10
Purchase #5	$199.78	5.516%	$210.7999	$210.80	$210.80	$210.80
Purchase #6	$105.36	4.683%	$110.294	$110.29	$110.30	$110.30
Purchase #7	$126.85	10.196%	$139.7836	$139.78	$139.80	$139.80
7 purchase totals =	$999.22		$1,087.8133	$1,087.80	$1,087.85	$1,087.80