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	$32.73	8.292%	$35.444	$35.44	$35.45	$35.40
Purchase #2	$96.89	8.787%	$105.4037	$105.40	$105.40	$105.40
Purchase #3	$168.44	10.298%	$185.786	$185.79	$185.80	$185.80
Purchase #4	$10.75	8.332%	$11.6457	$11.65	$11.65	$11.60
Purchase #5	$113.28	12.200%	$127.1002	$127.10	$127.10	$127.10
Purchase #6	$66.32	11.433%	$73.9024	$73.90	$73.90	$73.90
Purchase #7	$120.87	13.371%	$137.0315	$137.03	$137.05	$137.00
7 purchase totals =	$609.28		$676.3135	$676.31	$676.35	$676.20