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	$105.42	4.368%	$110.0247	$110.02	$110.00	$110.00
Purchase #2	$100.60	12.163%	$112.836	$112.84	$112.85	$112.80
Purchase #3	$213.52	4.825%	$223.8223	$223.82	$223.80	$223.80
Purchase #4	$101.76	3.297%	$105.115	$105.12	$105.10	$105.10
Purchase #5	$84.84	7.718%	$91.388	$91.39	$91.40	$91.40
Purchase #6	$103.94	13.327%	$117.7921	$117.79	$117.80	$117.80
Purchase #7	$199.67	4.478%	$208.6112	$208.61	$208.60	$208.60
7 purchase totals =	$909.75		$969.5893	$969.59	$969.55	$969.50