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	$167.99	8.335%	$181.992	$181.99	$182.00	$182.00
Purchase #2	$159.33	12.123%	$178.6456	$178.65	$178.65	$178.60
Purchase #3	$46.56	11.546%	$51.9358	$51.94	$51.95	$51.90
Purchase #4	$72.89	7.679%	$78.4872	$78.49	$78.50	$78.50
Purchase #5	$248.55	4.350%	$259.3619	$259.36	$259.35	$259.40
Purchase #6	$76.35	7.571%	$82.1305	$82.13	$82.15	$82.10
Purchase #7	$233.90	11.546%	$260.9061	$260.91	$260.90	$260.90
7 purchase totals =	$1,005.57		$1,093.4591	$1,093.47	$1,093.50	$1,093.40