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	$195.30	7.194%	$209.3499	$209.35	$209.35	$209.30
Purchase #2	$161.92	3.348%	$167.3411	$167.34	$167.35	$167.30
Purchase #3	$158.71	4.536%	$165.9091	$165.91	$165.90	$165.90
Purchase #4	$187.78	5.119%	$197.3925	$197.39	$197.40	$197.40
Purchase #5	$64.91	3.289%	$67.0449	$67.04	$67.05	$67.00
Purchase #6	$138.63	10.595%	$153.3178	$153.32	$153.30	$153.30
Purchase #7	$63.44	13.867%	$72.2372	$72.24	$72.25	$72.20
7 purchase totals =	$970.69		$1,032.5925	$1,032.59	$1,032.60	$1,032.40