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	$59.32	3.327%	$61.2936	$61.29	$61.30	$61.30
Purchase #2	$44.34	4.607%	$46.3827	$46.38	$46.40	$46.40
Purchase #3	$103.74	10.372%	$114.4999	$114.50	$114.50	$114.50
Purchase #4	$243.93	8.551%	$264.7885	$264.79	$264.80	$264.80
Purchase #5	$234.91	8.809%	$255.6032	$255.60	$255.60	$255.60
Purchase #6	$9.59	12.389%	$10.7781	$10.78	$10.80	$10.80
Purchase #7	$236.63	8.445%	$256.6134	$256.61	$256.60	$256.60
7 purchase totals =	$932.46		$1,009.9594	$1,009.95	$1,010.00	$1,010.00