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	$176.58	11.222%	$196.3958	$196.40	$196.40	$196.40
Purchase #2	$57.43	7.629%	$61.8113	$61.81	$61.80	$61.80
Purchase #3	$82.50	11.438%	$91.9364	$91.94	$91.95	$91.90
Purchase #4	$100.41	13.592%	$114.0577	$114.06	$114.05	$114.10
Purchase #5	$71.90	7.447%	$77.2544	$77.25	$77.25	$77.30
Purchase #6	$166.66	11.417%	$185.6876	$185.69	$185.70	$185.70
Purchase #7	$236.87	4.726%	$248.0645	$248.06	$248.05	$248.10
7 purchase totals =	$892.35		$975.2077	$975.21	$975.20	$975.30