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	$191.67	8.739%	$208.42	$208.42	$208.40	$208.40
Purchase #2	$168.97	7.575%	$181.7695	$181.77	$181.75	$181.80
Purchase #3	$87.38	7.863%	$94.2507	$94.25	$94.25	$94.30
Purchase #4	$190.48	5.150%	$200.2897	$200.29	$200.30	$200.30
Purchase #5	$53.36	7.637%	$57.4351	$57.44	$57.45	$57.40
Purchase #6	$181.42	8.400%	$196.6593	$196.66	$196.65	$196.70
Purchase #7	$182.89	3.612%	$189.496	$189.50	$189.50	$189.50
7 purchase totals =	$1,056.17		$1,128.3203	$1,128.33	$1,128.30	$1,128.40