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	$206.35	4.695%	$216.0381	$216.04	$216.05	$216.00
Purchase #2	$223.63	8.162%	$241.8827	$241.88	$241.90	$241.90
Purchase #3	$11.91	10.808%	$13.1972	$13.20	$13.20	$13.20
Purchase #4	$235.54	10.801%	$260.9807	$260.98	$261.00	$261.00
Purchase #5	$107.52	3.645%	$111.4391	$111.44	$111.45	$111.40
Purchase #6	$159.50	4.626%	$166.8785	$166.88	$166.90	$166.90
Purchase #7	$146.87	3.608%	$152.1691	$152.17	$152.15	$152.20
7 purchase totals =	$1,091.32		$1,162.5854	$1,162.59	$1,162.65	$1,162.60