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	$182.94	7.127%	$195.9781	$195.98	$196.00	$196.00
Purchase #2	$168.88	11.197%	$187.7895	$187.79	$187.80	$187.80
Purchase #3	$168.87	4.679%	$176.7714	$176.77	$176.75	$176.80
Purchase #4	$99.74	8.173%	$107.8918	$107.89	$107.90	$107.90
Purchase #5	$43.58	3.712%	$45.1977	$45.20	$45.20	$45.20
Purchase #6	$117.64	11.211%	$130.8286	$130.83	$130.85	$130.80
Purchase #7	$243.47	9.621%	$266.8942	$266.89	$266.90	$266.90
7 purchase totals =	$1,025.12		$1,111.3513	$1,111.35	$1,111.40	$1,111.40