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	$195.67	13.115%	$221.3321	$221.33	$221.35	$221.30
Purchase #2	$219.55	10.208%	$241.9617	$241.96	$241.95	$242.00
Purchase #3	$156.43	10.600%	$173.0116	$173.01	$173.00	$173.00
Purchase #4	$126.69	10.812%	$140.3877	$140.39	$140.40	$140.40
Purchase #5	$56.39	5.858%	$59.6933	$59.69	$59.70	$59.70
Purchase #6	$168.39	6.746%	$179.7496	$179.75	$179.75	$179.70
Purchase #7	$26.64	4.675%	$27.8854	$27.89	$27.90	$27.90
7 purchase totals =	$949.76		$1,044.0214	$1,044.02	$1,044.05	$1,044.00