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	$95.94	10.438%	$105.9542	$105.95	$105.95	$106.00
Purchase #2	$71.61	6.510%	$76.2718	$76.27	$76.25	$76.30
Purchase #3	$78.89	12.266%	$88.5666	$88.57	$88.55	$88.60
Purchase #4	$192.39	13.318%	$218.0125	$218.01	$218.00	$218.00
Purchase #5	$155.50	6.844%	$166.1424	$166.14	$166.15	$166.10
Purchase #6	$219.52	4.369%	$229.1108	$229.11	$229.10	$229.10
Purchase #7	$139.72	3.437%	$144.5222	$144.52	$144.50	$144.50
7 purchase totals =	$953.57		$1,028.5805	$1,028.57	$1,028.50	$1,028.60