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	$192.30	13.129%	$217.5471	$217.55	$217.55	$217.50
Purchase #2	$72.53	8.208%	$78.4833	$78.48	$78.50	$78.50
Purchase #3	$99.56	6.803%	$106.3331	$106.33	$106.35	$106.30
Purchase #4	$236.28	12.155%	$264.9998	$265.00	$265.00	$265.00
Purchase #5	$176.51	3.407%	$182.5237	$182.52	$182.50	$182.50
Purchase #6	$82.73	5.726%	$87.4671	$87.47	$87.45	$87.50
Purchase #7	$88.77	9.559%	$97.2555	$97.26	$97.25	$97.30
7 purchase totals =	$948.68		$1,034.6096	$1,034.61	$1,034.60	$1,034.60