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	$176.81	10.202%	$194.8482	$194.85	$194.85	$194.80
Purchase #2	$155.40	3.316%	$160.5531	$160.55	$160.55	$160.60
Purchase #3	$84.28	7.798%	$90.8522	$90.85	$90.85	$90.90
Purchase #4	$149.69	4.146%	$155.8961	$155.90	$155.90	$155.90
Purchase #5	$153.69	4.456%	$160.5384	$160.54	$160.55	$160.50
Purchase #6	$189.74	12.817%	$214.059	$214.06	$214.05	$214.10
Purchase #7	$181.34	5.295%	$190.942	$190.94	$190.95	$190.90
7 purchase totals =	$1,090.95		$1,167.6890	$1,167.69	$1,167.70	$1,167.70