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	$140.96	7.654%	$151.7491	$151.75	$151.75	$151.70
Purchase #2	$194.65	8.358%	$210.9188	$210.92	$210.90	$210.90
Purchase #3	$61.37	9.644%	$67.2885	$67.29	$67.30	$67.30
Purchase #4	$244.76	6.849%	$261.5236	$261.52	$261.50	$261.50
Purchase #5	$155.63	10.129%	$171.3938	$171.39	$171.40	$171.40
Purchase #6	$205.98	5.741%	$217.8053	$217.81	$217.80	$217.80
Purchase #7	$172.88	13.825%	$196.7807	$196.78	$196.80	$196.80
7 purchase totals =	$1,176.23		$1,277.4598	$1,277.46	$1,277.45	$1,277.40