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	$233.80	5.446%	$246.5327	$246.53	$246.55	$246.50
Purchase #2	$226.71	7.872%	$244.5566	$244.56	$244.55	$244.60
Purchase #3	$78.73	6.220%	$83.627	$83.63	$83.65	$83.60
Purchase #4	$34.90	8.565%	$37.8892	$37.89	$37.90	$37.90
Purchase #5	$177.74	3.217%	$183.4579	$183.46	$183.45	$183.50
Purchase #6	$142.92	4.809%	$149.793	$149.79	$149.80	$149.80
Purchase #7	$63.73	12.119%	$71.4534	$71.45	$71.45	$71.50
7 purchase totals =	$958.53		$1,017.3098	$1,017.31	$1,017.35	$1,017.40