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	$177.97	10.767%	$197.132	$197.13	$197.15	$197.10
Purchase #2	$209.27	6.113%	$222.0627	$222.06	$222.05	$222.10
Purchase #3	$50.31	13.721%	$57.213	$57.21	$57.20	$57.20
Purchase #4	$74.83	10.212%	$82.4716	$82.47	$82.45	$82.50
Purchase #5	$93.33	7.565%	$100.3904	$100.39	$100.40	$100.40
Purchase #6	$175.49	12.867%	$198.0703	$198.07	$198.05	$198.10
Purchase #7	$172.75	5.457%	$182.177	$182.18	$182.20	$182.20
7 purchase totals =	$953.95		$1,039.5170	$1,039.51	$1,039.50	$1,039.60