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	$181.64	8.778%	$197.5844	$197.58	$197.60	$197.60
Purchase #2	$142.37	9.258%	$155.5506	$155.55	$155.55	$155.60
Purchase #3	$17.65	5.539%	$18.6276	$18.63	$18.65	$18.60
Purchase #4	$179.73	9.154%	$196.1825	$196.18	$196.20	$196.20
Purchase #5	$198.88	7.209%	$213.2173	$213.22	$213.20	$213.20
Purchase #6	$195.68	10.823%	$216.8584	$216.86	$216.85	$216.90
Purchase #7	$80.64	10.698%	$89.2669	$89.27	$89.25	$89.30
7 purchase totals =	$996.59		$1,087.2877	$1,087.29	$1,087.30	$1,087.40