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	$191.90	4.475%	$200.4875	$200.49	$200.50	$200.50
Purchase #2	$248.61	4.137%	$258.895	$258.90	$258.90	$258.90
Purchase #3	$218.69	12.800%	$246.6823	$246.68	$246.70	$246.70
Purchase #4	$91.98	3.713%	$95.3952	$95.40	$95.40	$95.40
Purchase #5	$13.33	8.494%	$14.4623	$14.46	$14.45	$14.50
Purchase #6	$79.56	3.442%	$82.2985	$82.30	$82.30	$82.30
Purchase #7	$138.46	4.226%	$144.3113	$144.31	$144.30	$144.30
7 purchase totals =	$982.53		$1,042.5321	$1,042.54	$1,042.55	$1,042.60