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	$174.93	10.132%	$192.6539	$192.65	$192.65	$192.70
Purchase #2	$183.63	10.600%	$203.0948	$203.09	$203.10	$203.10
Purchase #3	$81.81	10.297%	$90.234	$90.23	$90.25	$90.20
Purchase #4	$162.29	8.388%	$175.9029	$175.90	$175.90	$175.90
Purchase #5	$20.89	4.683%	$21.8683	$21.87	$21.85	$21.90
Purchase #6	$181.28	8.472%	$196.638	$196.64	$196.65	$196.60
Purchase #7	$184.27	11.753%	$205.9273	$205.93	$205.95	$205.90
7 purchase totals =	$989.10		$1,086.3192	$1,086.31	$1,086.35	$1,086.30