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	$182.50	7.321%	$195.8608	$195.86	$195.85	$195.90
Purchase #2	$194.72	7.812%	$209.9315	$209.93	$209.95	$209.90
Purchase #3	$127.34	13.467%	$144.4889	$144.49	$144.50	$144.50
Purchase #4	$86.46	12.103%	$96.9243	$96.92	$96.90	$96.90
Purchase #5	$67.80	3.789%	$70.3689	$70.37	$70.35	$70.40
Purchase #6	$75.33	10.686%	$83.3798	$83.38	$83.40	$83.40
Purchase #7	$130.28	10.861%	$144.4297	$144.43	$144.45	$144.40
7 purchase totals =	$864.43		$945.3839	$945.38	$945.40	$945.40