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	$87.73	7.771%	$94.5475	$94.55	$94.55	$94.50
Purchase #2	$129.28	10.288%	$142.5803	$142.58	$142.60	$142.60
Purchase #3	$242.52	12.453%	$272.721	$272.72	$272.70	$272.70
Purchase #4	$223.90	4.736%	$234.5039	$234.50	$234.50	$234.50
Purchase #5	$172.65	6.870%	$184.5111	$184.51	$184.50	$184.50
Purchase #6	$17.41	9.467%	$19.0582	$19.06	$19.05	$19.10
Purchase #7	$70.65	10.451%	$78.0336	$78.03	$78.05	$78.00
7 purchase totals =	$944.14		$1,025.9556	$1,025.95	$1,025.95	$1,025.90