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	$109.25	4.591%	$114.2657	$114.27	$114.25	$114.30
Purchase #2	$234.80	12.348%	$263.7931	$263.79	$263.80	$263.80
Purchase #3	$200.46	3.827%	$208.1316	$208.13	$208.15	$208.10
Purchase #4	$89.93	12.152%	$100.8583	$100.86	$100.85	$100.90
Purchase #5	$104.70	8.278%	$113.3671	$113.37	$113.35	$113.40
Purchase #6	$214.40	13.411%	$243.1532	$243.15	$243.15	$243.20
Purchase #7	$27.93	12.410%	$31.3961	$31.40	$31.40	$31.40
7 purchase totals =	$981.47		$1,074.9651	$1,074.97	$1,074.95	$1,075.10