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	$95.55	6.717%	$101.9681	$101.97	$101.95	$102.00
Purchase #2	$43.40	4.256%	$45.2471	$45.25	$45.25	$45.20
Purchase #3	$117.88	7.744%	$127.0086	$127.01	$127.00	$127.00
Purchase #4	$56.80	4.829%	$59.5429	$59.54	$59.55	$59.50
Purchase #5	$195.48	6.664%	$208.5068	$208.51	$208.50	$208.50
Purchase #6	$222.88	5.535%	$235.2164	$235.22	$235.20	$235.20
Purchase #7	$159.72	3.125%	$164.7113	$164.71	$164.70	$164.70
7 purchase totals =	$891.71		$942.2012	$942.21	$942.15	$942.10