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	$197.54	11.730%	$220.7114	$220.71	$220.70	$220.70
Purchase #2	$69.43	11.820%	$77.6366	$77.64	$77.65	$77.60
Purchase #3	$35.76	8.868%	$38.9312	$38.93	$38.95	$38.90
Purchase #4	$77.67	10.216%	$85.6048	$85.60	$85.60	$85.60
Purchase #5	$93.56	11.128%	$103.9714	$103.97	$103.95	$104.00
Purchase #6	$211.86	5.144%	$222.7581	$222.76	$222.75	$222.80
Purchase #7	$243.77	12.219%	$273.5563	$273.56	$273.55	$273.60
7 purchase totals =	$929.59		$1,023.1698	$1,023.17	$1,023.15	$1,023.20