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	$86.36	5.685%	$91.2696	$91.27	$91.25	$91.30
Purchase #2	$13.59	7.426%	$14.5992	$14.60	$14.60	$14.60
Purchase #3	$34.71	3.410%	$35.8936	$35.89	$35.90	$35.90
Purchase #4	$78.76	13.328%	$89.2571	$89.26	$89.25	$89.30
Purchase #5	$130.54	3.165%	$134.6716	$134.67	$134.65	$134.70
Purchase #6	$238.52	5.522%	$251.6911	$251.69	$251.70	$251.70
Purchase #7	$94.66	10.763%	$104.8483	$104.85	$104.85	$104.80
7 purchase totals =	$677.14		$722.2305	$722.23	$722.20	$722.30