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	$68.34	13.402%	$77.4989	$77.50	$77.50	$77.50
Purchase #2	$207.64	7.612%	$223.4456	$223.45	$223.45	$223.40
Purchase #3	$78.29	4.843%	$82.0816	$82.08	$82.10	$82.10
Purchase #4	$187.98	3.457%	$194.4785	$194.48	$194.50	$194.50
Purchase #5	$239.69	9.443%	$262.3239	$262.32	$262.30	$262.30
Purchase #6	$207.79	5.836%	$219.9166	$219.92	$219.90	$219.90
Purchase #7	$32.29	10.731%	$35.755	$35.76	$35.75	$35.80
7 purchase totals =	$1,022.02		$1,095.5001	$1,095.51	$1,095.50	$1,095.50