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	$164.25	10.277%	$181.13	$181.13	$181.15	$181.10
Purchase #2	$201.27	10.680%	$222.7656	$222.77	$222.75	$222.80
Purchase #3	$163.67	5.119%	$172.0483	$172.05	$172.05	$172.00
Purchase #4	$250.64	5.517%	$264.4678	$264.47	$264.45	$264.50
Purchase #5	$83.69	13.383%	$94.8902	$94.89	$94.90	$94.90
Purchase #6	$179.98	10.482%	$198.8455	$198.85	$198.85	$198.80
Purchase #7	$233.61	7.601%	$251.3667	$251.37	$251.35	$251.40
7 purchase totals =	$1,277.11		$1,385.5141	$1,385.53	$1,385.50	$1,385.50