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	$205.32	13.807%	$233.6685	$233.67	$233.65	$233.70
Purchase #2	$247.44	10.713%	$273.9482	$273.95	$273.95	$273.90
Purchase #3	$7.98	4.172%	$8.3129	$8.31	$8.30	$8.30
Purchase #4	$200.43	13.292%	$227.0712	$227.07	$227.05	$227.10
Purchase #5	$30.83	4.251%	$32.1406	$32.14	$32.15	$32.10
Purchase #6	$43.75	4.394%	$45.6724	$45.67	$45.65	$45.70
Purchase #7	$192.85	8.123%	$208.5152	$208.52	$208.50	$208.50
7 purchase totals =	$928.60		$1,029.3290	$1,029.33	$1,029.25	$1,029.30