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	$196.89	13.208%	$222.8952	$222.90	$222.90	$222.90
Purchase #2	$186.34	9.453%	$203.9547	$203.95	$203.95	$204.00
Purchase #3	$31.65	8.829%	$34.4444	$34.44	$34.45	$34.40
Purchase #4	$171.82	10.838%	$190.4419	$190.44	$190.45	$190.40
Purchase #5	$43.41	10.742%	$48.0731	$48.07	$48.05	$48.10
Purchase #6	$198.27	10.848%	$219.7783	$219.78	$219.80	$219.80
Purchase #7	$248.55	11.512%	$277.1631	$277.16	$277.15	$277.20
7 purchase totals =	$1,076.93		$1,196.7507	$1,196.74	$1,196.75	$1,196.80