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	$75.70	8.428%	$82.08	$82.08	$82.10	$82.10
Purchase #2	$112.69	12.755%	$127.0636	$127.06	$127.05	$127.10
Purchase #3	$234.97	8.595%	$255.1657	$255.17	$255.15	$255.20
Purchase #4	$245.43	5.362%	$258.59	$258.59	$258.60	$258.60
Purchase #5	$12.25	10.219%	$13.5018	$13.50	$13.50	$13.50
Purchase #6	$203.72	4.702%	$213.2989	$213.30	$213.30	$213.30
Purchase #7	$85.71	6.527%	$91.3043	$91.30	$91.30	$91.30
7 purchase totals =	$970.47		$1,041.0043	$1,041.00	$1,041.00	$1,041.10