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	$40.94	8.676%	$44.492	$44.49	$44.50	$44.50
Purchase #2	$143.43	3.523%	$148.483	$148.48	$148.50	$148.50
Purchase #3	$128.91	10.470%	$142.4069	$142.41	$142.40	$142.40
Purchase #4	$154.51	6.479%	$164.5207	$164.52	$164.50	$164.50
Purchase #5	$193.85	9.424%	$212.1184	$212.12	$212.10	$212.10
Purchase #6	$229.99	12.478%	$258.6882	$258.69	$258.70	$258.70
Purchase #7	$69.72	12.264%	$78.2705	$78.27	$78.25	$78.30
7 purchase totals =	$961.35		$1,048.9797	$1,048.98	$1,048.95	$1,049.00