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	$194.71	5.625%	$205.6624	$205.66	$205.65	$205.70
Purchase #2	$69.82	11.856%	$78.0979	$78.10	$78.10	$78.10
Purchase #3	$150.85	9.377%	$164.9952	$165.00	$165.00	$165.00
Purchase #4	$71.75	4.736%	$75.1481	$75.15	$75.15	$75.10
Purchase #5	$21.37	5.225%	$22.4866	$22.49	$22.50	$22.50
Purchase #6	$146.51	4.482%	$153.0766	$153.08	$153.10	$153.10
Purchase #7	$48.59	13.412%	$55.1069	$55.11	$55.10	$55.10
7 purchase totals =	$703.60		$754.5737	$754.59	$754.60	$754.60