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	$119.52	4.650%	$125.0777	$125.08	$125.10	$125.10
Purchase #2	$225.92	13.508%	$256.4373	$256.44	$256.45	$256.40
Purchase #3	$242.42	10.375%	$267.5711	$267.57	$267.55	$267.60
Purchase #4	$6.47	3.713%	$6.7102	$6.71	$6.70	$6.70
Purchase #5	$237.64	13.179%	$268.9586	$268.96	$268.95	$269.00
Purchase #6	$159.71	7.390%	$171.5126	$171.51	$171.50	$171.50
Purchase #7	$54.66	8.800%	$59.4701	$59.47	$59.45	$59.50
7 purchase totals =	$1,046.34		$1,155.7376	$1,155.74	$1,155.70	$1,155.80