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	$167.45	11.398%	$186.536	$186.54	$186.55	$186.50
Purchase #2	$72.91	12.262%	$81.8502	$81.85	$81.85	$81.90
Purchase #3	$75.52	3.132%	$77.8853	$77.89	$77.90	$77.90
Purchase #4	$210.44	8.148%	$227.5867	$227.59	$227.60	$227.60
Purchase #5	$149.72	8.615%	$162.6184	$162.62	$162.60	$162.60
Purchase #6	$170.51	8.565%	$185.1142	$185.11	$185.10	$185.10
Purchase #7	$112.79	13.297%	$127.7877	$127.79	$127.80	$127.80
7 purchase totals =	$959.34		$1,049.3785	$1,049.39	$1,049.40	$1,049.40