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	$103.57	10.675%	$114.6261	$114.63	$114.65	$114.60
Purchase #2	$160.46	7.378%	$172.2987	$172.30	$172.30	$172.30
Purchase #3	$69.38	13.308%	$78.6131	$78.61	$78.60	$78.60
Purchase #4	$50.38	8.602%	$54.7137	$54.71	$54.70	$54.70
Purchase #5	$165.48	12.445%	$186.074	$186.07	$186.05	$186.10
Purchase #6	$209.66	10.302%	$231.2592	$231.26	$231.25	$231.30
Purchase #7	$176.91	12.440%	$198.9176	$198.92	$198.90	$198.90
7 purchase totals =	$935.84		$1,036.5024	$1,036.50	$1,036.45	$1,036.50