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	$118.67	7.314%	$127.3495	$127.35	$127.35	$127.30
Purchase #2	$224.80	8.655%	$244.2564	$244.26	$244.25	$244.30
Purchase #3	$27.45	3.799%	$28.4928	$28.49	$28.50	$28.50
Purchase #4	$54.89	12.389%	$61.6903	$61.69	$61.70	$61.70
Purchase #5	$247.66	13.790%	$281.8123	$281.81	$281.80	$281.80
Purchase #6	$124.85	12.520%	$140.4812	$140.48	$140.50	$140.50
Purchase #7	$43.93	9.443%	$48.0783	$48.08	$48.10	$48.10
7 purchase totals =	$842.25		$932.1608	$932.16	$932.20	$932.20