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	$48.72	10.115%	$53.648	$53.65	$53.65	$53.60
Purchase #2	$77.37	4.239%	$80.6497	$80.65	$80.65	$80.60
Purchase #3	$106.41	9.842%	$116.8829	$116.88	$116.90	$116.90
Purchase #4	$111.86	11.299%	$124.4991	$124.50	$124.50	$124.50
Purchase #5	$120.86	4.267%	$126.0171	$126.02	$126.00	$126.00
Purchase #6	$179.59	13.744%	$204.2728	$204.27	$204.25	$204.30
Purchase #7	$110.30	12.291%	$123.857	$123.86	$123.85	$123.90
7 purchase totals =	$755.11		$829.8266	$829.83	$829.80	$829.80