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	$158.81	9.604%	$174.0621	$174.06	$174.05	$174.10
Purchase #2	$220.89	13.157%	$249.9525	$249.95	$249.95	$250.00
Purchase #3	$56.27	4.614%	$58.8663	$58.87	$58.85	$58.90
Purchase #4	$113.32	9.340%	$123.9041	$123.90	$123.90	$123.90
Purchase #5	$31.79	3.608%	$32.937	$32.94	$32.95	$32.90
Purchase #6	$216.57	9.130%	$236.3428	$236.34	$236.35	$236.30
Purchase #7	$134.98	12.499%	$151.8512	$151.85	$151.85	$151.90
7 purchase totals =	$932.63		$1,027.9160	$1,027.91	$1,027.90	$1,028.00