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	$199.25	5.550%	$210.3084	$210.31	$210.30	$210.30
Purchase #2	$24.58	7.498%	$26.423	$26.42	$26.40	$26.40
Purchase #3	$208.31	13.563%	$236.5631	$236.56	$236.55	$236.60
Purchase #4	$177.44	4.563%	$185.5366	$185.54	$185.55	$185.50
Purchase #5	$50.98	6.873%	$54.4839	$54.48	$54.50	$54.50
Purchase #6	$151.56	6.117%	$160.8309	$160.83	$160.85	$160.80
Purchase #7	$122.32	12.330%	$137.4021	$137.40	$137.40	$137.40
7 purchase totals =	$934.44		$1,011.5480	$1,011.54	$1,011.55	$1,011.50