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	$169.37	11.216%	$188.3665	$188.37	$188.35	$188.40
Purchase #2	$91.97	11.440%	$102.4914	$102.49	$102.50	$102.50
Purchase #3	$73.25	7.448%	$78.7057	$78.71	$78.70	$78.70
Purchase #4	$164.64	4.712%	$172.3978	$172.40	$172.40	$172.40
Purchase #5	$195.94	8.365%	$212.3304	$212.33	$212.35	$212.30
Purchase #6	$152.81	9.644%	$167.547	$167.55	$167.55	$167.50
Purchase #7	$188.86	5.438%	$199.1302	$199.13	$199.15	$199.10
7 purchase totals =	$1,036.84		$1,120.9690	$1,120.98	$1,121.00	$1,120.90