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	$176.54	8.417%	$191.3994	$191.40	$191.40	$191.40
Purchase #2	$213.32	9.519%	$233.6259	$233.63	$233.65	$233.60
Purchase #3	$56.82	3.504%	$58.811	$58.81	$58.80	$58.80
Purchase #4	$190.75	13.196%	$215.9214	$215.92	$215.90	$215.90
Purchase #5	$118.84	11.790%	$132.8512	$132.85	$132.85	$132.90
Purchase #6	$184.94	6.368%	$196.717	$196.72	$196.70	$196.70
Purchase #7	$78.28	5.469%	$82.5611	$82.56	$82.55	$82.60
7 purchase totals =	$1,019.49		$1,111.8870	$1,111.89	$1,111.85	$1,111.90