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	$188.43	9.197%	$205.7599	$205.76	$205.75	$205.80
Purchase #2	$231.89	10.538%	$256.3266	$256.33	$256.35	$256.30
Purchase #3	$85.59	8.376%	$92.759	$92.76	$92.75	$92.80
Purchase #4	$168.45	3.241%	$173.9095	$173.91	$173.90	$173.90
Purchase #5	$141.94	11.652%	$158.4788	$158.48	$158.50	$158.50
Purchase #6	$156.82	7.112%	$167.973	$167.97	$167.95	$168.00
Purchase #7	$34.94	11.665%	$39.0158	$39.02	$39.00	$39.00
7 purchase totals =	$1,008.06		$1,094.2226	$1,094.23	$1,094.20	$1,094.30