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	$176.95	11.227%	$196.8162	$196.82	$196.80	$196.80
Purchase #2	$67.52	7.593%	$72.6468	$72.65	$72.65	$72.60
Purchase #3	$38.81	8.541%	$42.1248	$42.12	$42.10	$42.10
Purchase #4	$96.69	9.633%	$106.0041	$106.00	$106.00	$106.00
Purchase #5	$73.72	3.472%	$76.2796	$76.28	$76.30	$76.30
Purchase #6	$14.69	3.383%	$15.187	$15.19	$15.20	$15.20
Purchase #7	$52.68	8.606%	$57.2136	$57.21	$57.20	$57.20
7 purchase totals =	$521.06		$566.2721	$566.27	$566.25	$566.20