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	$178.41	9.450%	$195.2697	$195.27	$195.25	$195.30
Purchase #2	$171.32	9.121%	$186.9461	$186.95	$186.95	$186.90
Purchase #3	$35.95	9.827%	$39.4828	$39.48	$39.50	$39.50
Purchase #4	$103.76	10.770%	$114.935	$114.94	$114.95	$114.90
Purchase #5	$173.82	9.521%	$190.3694	$190.37	$190.35	$190.40
Purchase #6	$250.92	9.861%	$275.6632	$275.66	$275.65	$275.70
Purchase #7	$72.62	8.340%	$78.6765	$78.68	$78.70	$78.70
7 purchase totals =	$986.80		$1,081.3427	$1,081.35	$1,081.35	$1,081.40