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	$142.65	7.680%	$153.6055	$153.61	$153.60	$153.60
Purchase #2	$103.51	9.528%	$113.3724	$113.37	$113.35	$113.40
Purchase #3	$78.34	9.139%	$85.4995	$85.50	$85.50	$85.50
Purchase #4	$48.35	11.516%	$53.918	$53.92	$53.90	$53.90
Purchase #5	$60.82	11.157%	$67.6057	$67.61	$67.60	$67.60
Purchase #6	$188.32	6.632%	$200.8094	$200.81	$200.80	$200.80
Purchase #7	$209.92	12.649%	$236.4728	$236.47	$236.45	$236.50
7 purchase totals =	$831.91		$911.2833	$911.29	$911.20	$911.30