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	$126.63	12.618%	$142.6082	$142.61	$142.60	$142.60
Purchase #2	$30.49	9.300%	$33.3256	$33.33	$33.35	$33.30
Purchase #3	$39.36	9.147%	$42.9603	$42.96	$42.95	$43.00
Purchase #4	$231.47	3.724%	$240.0899	$240.09	$240.10	$240.10
Purchase #5	$236.76	8.293%	$256.3945	$256.39	$256.40	$256.40
Purchase #6	$222.75	13.698%	$253.2623	$253.26	$253.25	$253.30
Purchase #7	$86.29	9.802%	$94.7481	$94.75	$94.75	$94.70
7 purchase totals =	$973.75		$1,063.3889	$1,063.39	$1,063.40	$1,063.40