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	$186.82	5.423%	$196.9512	$196.95	$196.95	$197.00
Purchase #2	$54.84	10.415%	$60.5516	$60.55	$60.55	$60.60
Purchase #3	$53.47	13.671%	$60.7799	$60.78	$60.80	$60.80
Purchase #4	$96.51	5.595%	$101.9097	$101.91	$101.90	$101.90
Purchase #5	$112.57	9.762%	$123.5591	$123.56	$123.55	$123.60
Purchase #6	$153.69	3.186%	$158.5866	$158.59	$158.60	$158.60
Purchase #7	$99.53	3.730%	$103.2425	$103.24	$103.25	$103.20
7 purchase totals =	$757.43		$805.5806	$805.58	$805.60	$805.70