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	$67.92	7.455%	$72.9834	$72.98	$73.00	$73.00
Purchase #2	$187.75	4.640%	$196.4616	$196.46	$196.45	$196.50
Purchase #3	$196.56	11.706%	$219.5693	$219.57	$219.55	$219.60
Purchase #4	$129.40	3.365%	$133.7543	$133.75	$133.75	$133.80
Purchase #5	$57.32	8.709%	$62.312	$62.31	$62.30	$62.30
Purchase #6	$153.63	9.153%	$167.6918	$167.69	$167.70	$167.70
Purchase #7	$204.48	12.345%	$229.7231	$229.72	$229.70	$229.70
7 purchase totals =	$997.06		$1,082.4955	$1,082.48	$1,082.45	$1,082.60