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	$190.35	11.309%	$211.8767	$211.88	$211.90	$211.90
Purchase #2	$171.69	6.257%	$182.4326	$182.43	$182.45	$182.40
Purchase #3	$147.33	4.458%	$153.898	$153.90	$153.90	$153.90
Purchase #4	$126.90	10.197%	$139.84	$139.84	$139.85	$139.80
Purchase #5	$143.73	8.807%	$156.3883	$156.39	$156.40	$156.40
Purchase #6	$93.54	12.746%	$105.4626	$105.46	$105.45	$105.50
Purchase #7	$142.67	12.828%	$160.9717	$160.97	$160.95	$161.00
7 purchase totals =	$1,016.21		$1,110.8699	$1,110.87	$1,110.90	$1,110.90