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	$105.25	7.825%	$113.4858	$113.49	$113.50	$113.50
Purchase #2	$191.30	9.713%	$209.881	$209.88	$209.90	$209.90
Purchase #3	$137.88	13.371%	$156.3159	$156.32	$156.30	$156.30
Purchase #4	$165.55	5.561%	$174.7562	$174.76	$174.75	$174.80
Purchase #5	$11.31	11.293%	$12.5872	$12.59	$12.60	$12.60
Purchase #6	$249.28	12.267%	$279.8592	$279.86	$279.85	$279.90
Purchase #7	$146.39	8.166%	$158.3442	$158.34	$158.35	$158.30
7 purchase totals =	$1,006.96		$1,105.2295	$1,105.24	$1,105.25	$1,105.30