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	$31.98	11.391%	$35.6228	$35.62	$35.60	$35.60
Purchase #2	$87.76	4.337%	$91.5662	$91.57	$91.55	$91.60
Purchase #3	$167.89	3.267%	$173.375	$173.38	$173.40	$173.40
Purchase #4	$194.72	11.167%	$216.4644	$216.46	$216.45	$216.50
Purchase #5	$69.35	11.421%	$77.2705	$77.27	$77.25	$77.30
Purchase #6	$239.39	3.254%	$247.1798	$247.18	$247.20	$247.20
Purchase #7	$155.67	4.434%	$162.5724	$162.57	$162.55	$162.60
7 purchase totals =	$946.76		$1,004.0511	$1,004.05	$1,004.00	$1,004.20