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	$191.96	7.238%	$205.8541	$205.85	$205.85	$205.90
Purchase #2	$130.55	8.388%	$141.5005	$141.50	$141.50	$141.50
Purchase #3	$173.69	5.281%	$182.8626	$182.86	$182.85	$182.90
Purchase #4	$151.93	3.298%	$156.9407	$156.94	$156.95	$156.90
Purchase #5	$78.34	9.853%	$86.0588	$86.06	$86.05	$86.10
Purchase #6	$134.81	5.331%	$141.9967	$142.00	$142.00	$142.00
Purchase #7	$165.94	3.614%	$171.9371	$171.94	$171.95	$171.90
7 purchase totals =	$1,027.22		$1,087.1505	$1,087.15	$1,087.15	$1,087.20