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	$221.79	5.481%	$233.9463	$233.95	$233.95	$233.90
Purchase #2	$29.52	10.319%	$32.5662	$32.57	$32.55	$32.60
Purchase #3	$193.52	3.571%	$200.4306	$200.43	$200.45	$200.40
Purchase #4	$120.79	11.348%	$134.4972	$134.50	$134.50	$134.50
Purchase #5	$224.30	8.662%	$243.7289	$243.73	$243.75	$243.70
Purchase #6	$173.62	13.775%	$197.5362	$197.54	$197.55	$197.50
Purchase #7	$82.34	8.188%	$89.082	$89.08	$89.10	$89.10
7 purchase totals =	$1,045.88		$1,131.7874	$1,131.80	$1,131.85	$1,131.70