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	$162.64	11.320%	$181.0508	$181.05	$181.05	$181.10
Purchase #2	$28.64	13.782%	$32.5872	$32.59	$32.60	$32.60
Purchase #3	$52.88	11.355%	$58.8845	$58.88	$58.90	$58.90
Purchase #4	$126.76	7.796%	$136.6422	$136.64	$136.65	$136.60
Purchase #5	$131.61	7.508%	$141.4913	$141.49	$141.50	$141.50
Purchase #6	$167.78	8.174%	$181.4943	$181.49	$181.50	$181.50
Purchase #7	$245.57	3.721%	$254.7077	$254.71	$254.70	$254.70
7 purchase totals =	$915.88		$986.8580	$986.85	$986.90	$986.90