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	$198.95	7.594%	$214.0583	$214.06	$214.05	$214.10
Purchase #2	$82.26	10.627%	$91.0018	$91.00	$91.00	$91.00
Purchase #3	$29.25	13.173%	$33.1031	$33.10	$33.10	$33.10
Purchase #4	$156.95	4.586%	$164.1477	$164.15	$164.15	$164.10
Purchase #5	$128.56	12.267%	$144.3305	$144.33	$144.35	$144.30
Purchase #6	$144.92	13.314%	$164.2146	$164.21	$164.20	$164.20
Purchase #7	$183.99	11.856%	$205.8039	$205.80	$205.80	$205.80
7 purchase totals =	$924.88		$1,016.6599	$1,016.65	$1,016.65	$1,016.60