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	$192.51	5.661%	$203.408	$203.41	$203.40	$203.40
Purchase #2	$80.26	7.177%	$86.0203	$86.02	$86.00	$86.00
Purchase #3	$224.33	6.136%	$238.0949	$238.09	$238.10	$238.10
Purchase #4	$61.48	6.558%	$65.5119	$65.51	$65.50	$65.50
Purchase #5	$154.77	11.377%	$172.3782	$172.38	$172.40	$172.40
Purchase #6	$143.45	5.308%	$151.0643	$151.06	$151.05	$151.10
Purchase #7	$119.79	12.287%	$134.5086	$134.51	$134.50	$134.50
7 purchase totals =	$976.59		$1,050.9862	$1,050.98	$1,050.95	$1,051.00