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	$205.74	9.382%	$225.0425	$225.04	$225.05	$225.00
Purchase #2	$10.99	10.388%	$12.1316	$12.13	$12.15	$12.10
Purchase #3	$164.96	13.387%	$187.0432	$187.04	$187.05	$187.00
Purchase #4	$37.28	7.452%	$40.0581	$40.06	$40.05	$40.10
Purchase #5	$206.76	12.625%	$232.8635	$232.86	$232.85	$232.90
Purchase #6	$183.53	6.150%	$194.8171	$194.82	$194.80	$194.80
Purchase #7	$163.80	3.524%	$169.5723	$169.57	$169.55	$169.60
7 purchase totals =	$973.06		$1,061.5283	$1,061.52	$1,061.50	$1,061.50