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	$193.52	11.468%	$215.7129	$215.71	$215.70	$215.70
Purchase #2	$248.59	7.659%	$267.6295	$267.63	$267.65	$267.60
Purchase #3	$42.61	6.654%	$45.4453	$45.45	$45.45	$45.40
Purchase #4	$41.61	9.585%	$45.5983	$45.60	$45.60	$45.60
Purchase #5	$65.26	10.518%	$72.124	$72.12	$72.10	$72.10
Purchase #6	$186.91	4.820%	$195.9191	$195.92	$195.90	$195.90
Purchase #7	$176.74	4.435%	$184.5784	$184.58	$184.60	$184.60
7 purchase totals =	$955.24		$1,027.0075	$1,027.01	$1,027.00	$1,026.90