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	$117.43	6.495%	$125.0571	$125.06	$125.05	$125.10
Purchase #2	$41.29	11.251%	$45.9355	$45.94	$45.95	$45.90
Purchase #3	$18.38	3.663%	$19.0533	$19.05	$19.05	$19.10
Purchase #4	$152.91	7.573%	$164.4899	$164.49	$164.50	$164.50
Purchase #5	$54.51	8.450%	$59.1161	$59.12	$59.10	$59.10
Purchase #6	$171.83	5.153%	$180.6844	$180.68	$180.70	$180.70
Purchase #7	$99.94	11.691%	$111.624	$111.62	$111.60	$111.60
7 purchase totals =	$656.29		$705.9603	$705.96	$705.95	$706.00