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	$181.96	5.445%	$191.8677	$191.87	$191.85	$191.90
Purchase #2	$198.72	11.163%	$220.9031	$220.90	$220.90	$220.90
Purchase #3	$41.96	7.175%	$44.9706	$44.97	$44.95	$45.00
Purchase #4	$151.30	9.722%	$166.0094	$166.01	$166.00	$166.00
Purchase #5	$107.72	9.417%	$117.864	$117.86	$117.85	$117.90
Purchase #6	$160.49	11.747%	$179.3428	$179.34	$179.35	$179.30
Purchase #7	$40.85	3.653%	$42.3423	$42.34	$42.35	$42.30
7 purchase totals =	$883.00		$963.2999	$963.29	$963.25	$963.30