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	$76.38	9.172%	$83.3856	$83.39	$83.40	$83.40
Purchase #2	$141.31	4.350%	$147.457	$147.46	$147.45	$147.50
Purchase #3	$164.41	4.482%	$171.7789	$171.78	$171.80	$171.80
Purchase #4	$194.45	11.190%	$216.209	$216.21	$216.20	$216.20
Purchase #5	$27.65	12.174%	$31.0161	$31.02	$31.00	$31.00
Purchase #6	$126.69	11.786%	$141.6217	$141.62	$141.60	$141.60
Purchase #7	$205.71	13.552%	$233.5878	$233.59	$233.60	$233.60
7 purchase totals =	$936.60		$1,025.0561	$1,025.07	$1,025.05	$1,025.10