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	$153.64	11.851%	$171.8479	$171.85	$171.85	$171.80
Purchase #2	$215.28	5.462%	$227.0386	$227.04	$227.05	$227.00
Purchase #3	$173.31	5.357%	$182.5942	$182.59	$182.60	$182.60
Purchase #4	$98.73	13.148%	$111.711	$111.71	$111.70	$111.70
Purchase #5	$214.87	6.712%	$229.2921	$229.29	$229.30	$229.30
Purchase #6	$218.87	10.242%	$241.2867	$241.29	$241.30	$241.30
Purchase #7	$13.97	5.660%	$14.7607	$14.76	$14.75	$14.80
7 purchase totals =	$1,088.67		$1,178.5312	$1,178.53	$1,178.55	$1,178.50