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	$137.54	11.676%	$153.5992	$153.60	$153.60	$153.60
Purchase #2	$13.25	9.526%	$14.5122	$14.51	$14.50	$14.50
Purchase #3	$74.37	5.835%	$78.7095	$78.71	$78.70	$78.70
Purchase #4	$45.68	6.779%	$48.7766	$48.78	$48.80	$48.80
Purchase #5	$207.67	13.425%	$235.5497	$235.55	$235.55	$235.50
Purchase #6	$249.53	5.123%	$262.3134	$262.31	$262.30	$262.30
Purchase #7	$222.92	7.171%	$238.9056	$238.91	$238.90	$238.90
7 purchase totals =	$950.96		$1,032.3662	$1,032.37	$1,032.35	$1,032.30