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	$195.99	7.446%	$210.5834	$210.58	$210.60	$210.60
Purchase #2	$196.78	9.323%	$215.1258	$215.13	$215.15	$215.10
Purchase #3	$131.87	12.318%	$148.1137	$148.11	$148.10	$148.10
Purchase #4	$51.58	9.608%	$56.5358	$56.54	$56.55	$56.50
Purchase #5	$71.61	3.154%	$73.8686	$73.87	$73.85	$73.90
Purchase #6	$140.80	9.265%	$153.8451	$153.85	$153.85	$153.80
Purchase #7	$99.27	4.401%	$103.6389	$103.64	$103.65	$103.60
7 purchase totals =	$887.90		$961.7113	$961.72	$961.75	$961.60