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	$96.40	10.725%	$106.7389	$106.74	$106.75	$106.70
Purchase #2	$39.95	13.264%	$45.249	$45.25	$45.25	$45.20
Purchase #3	$167.93	12.266%	$188.5283	$188.53	$188.55	$188.50
Purchase #4	$171.77	13.164%	$194.3818	$194.38	$194.40	$194.40
Purchase #5	$63.71	12.781%	$71.8528	$71.85	$71.85	$71.90
Purchase #6	$123.67	3.184%	$127.6077	$127.61	$127.60	$127.60
Purchase #7	$114.50	9.592%	$125.4828	$125.48	$125.50	$125.50
7 purchase totals =	$777.93		$859.8413	$859.84	$859.90	$859.80