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	$186.46	5.141%	$196.0459	$196.05	$196.05	$196.00
Purchase #2	$197.74	12.200%	$221.8643	$221.86	$221.85	$221.90
Purchase #3	$28.99	10.855%	$32.1369	$32.14	$32.15	$32.10
Purchase #4	$184.60	11.335%	$205.5244	$205.52	$205.50	$205.50
Purchase #5	$180.37	3.624%	$186.9066	$186.91	$186.90	$186.90
Purchase #6	$114.42	7.544%	$123.0518	$123.05	$123.05	$123.10
Purchase #7	$131.56	7.529%	$141.4652	$141.47	$141.45	$141.50
7 purchase totals =	$1,024.14		$1,106.9951	$1,107.00	$1,106.95	$1,107.00