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	$42.59	7.248%	$45.6769	$45.68	$45.70	$45.70
Purchase #2	$83.91	9.778%	$92.1147	$92.11	$92.10	$92.10
Purchase #3	$109.29	6.192%	$116.0572	$116.06	$116.05	$116.10
Purchase #4	$132.96	3.483%	$137.591	$137.59	$137.60	$137.60
Purchase #5	$36.68	13.485%	$41.6263	$41.63	$41.65	$41.60
Purchase #6	$94.28	9.801%	$103.5204	$103.52	$103.50	$103.50
Purchase #7	$200.25	4.351%	$208.9629	$208.96	$208.95	$209.00
7 purchase totals =	$699.96		$745.5494	$745.55	$745.55	$745.60