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	$172.50	4.534%	$180.3212	$180.32	$180.30	$180.30
Purchase #2	$175.77	4.570%	$183.8027	$183.80	$183.80	$183.80
Purchase #3	$196.60	9.485%	$215.2475	$215.25	$215.25	$215.20
Purchase #4	$87.95	12.736%	$99.1513	$99.15	$99.15	$99.20
Purchase #5	$84.64	11.517%	$94.388	$94.39	$94.40	$94.40
Purchase #6	$100.31	5.812%	$106.14	$106.14	$106.15	$106.10
Purchase #7	$159.47	5.650%	$168.4801	$168.48	$168.50	$168.50
7 purchase totals =	$977.24		$1,047.5308	$1,047.53	$1,047.55	$1,047.50