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	$184.58	6.482%	$196.5445	$196.54	$196.55	$196.50
Purchase #2	$12.79	10.803%	$14.1717	$14.17	$14.15	$14.20
Purchase #3	$175.52	5.225%	$184.6909	$184.69	$184.70	$184.70
Purchase #4	$174.86	12.200%	$196.1929	$196.19	$196.20	$196.20
Purchase #5	$57.47	7.129%	$61.567	$61.57	$61.55	$61.60
Purchase #6	$150.57	9.873%	$165.4358	$165.44	$165.45	$165.40
Purchase #7	$241.79	8.564%	$262.4969	$262.50	$262.50	$262.50
7 purchase totals =	$997.58		$1,081.0997	$1,081.10	$1,081.10	$1,081.10