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	$249.25	13.437%	$282.7417	$282.74	$282.75	$282.70
Purchase #2	$105.67	7.349%	$113.4357	$113.44	$113.45	$113.40
Purchase #3	$98.70	7.838%	$106.4361	$106.44	$106.45	$106.40
Purchase #4	$217.60	7.331%	$233.5523	$233.55	$233.55	$233.60
Purchase #5	$85.40	4.844%	$89.5368	$89.54	$89.55	$89.50
Purchase #6	$88.87	13.409%	$100.7866	$100.79	$100.80	$100.80
Purchase #7	$77.68	7.621%	$83.6	$83.60	$83.60	$83.60
7 purchase totals =	$923.17		$1,010.0892	$1,010.10	$1,010.15	$1,010.00