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	$168.98	13.783%	$192.2705	$192.27	$192.25	$192.30
Purchase #2	$145.54	3.859%	$151.1564	$151.16	$151.15	$151.20
Purchase #3	$89.90	7.676%	$96.8007	$96.80	$96.80	$96.80
Purchase #4	$188.71	6.482%	$200.9422	$200.94	$200.95	$200.90
Purchase #5	$140.38	8.682%	$152.5678	$152.57	$152.55	$152.60
Purchase #6	$174.69	3.863%	$181.4383	$181.44	$181.45	$181.40
Purchase #7	$191.63	9.497%	$209.8291	$209.83	$209.85	$209.80
7 purchase totals =	$1,099.83		$1,185.0050	$1,185.01	$1,185.00	$1,185.00