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	$92.73	9.597%	$101.6293	$101.63	$101.65	$101.60
Purchase #2	$142.49	3.122%	$146.9385	$146.94	$146.95	$146.90
Purchase #3	$106.27	6.596%	$113.2796	$113.28	$113.30	$113.30
Purchase #4	$241.73	13.343%	$273.984	$273.98	$274.00	$274.00
Purchase #5	$34.59	6.653%	$36.8913	$36.89	$36.90	$36.90
Purchase #6	$109.89	12.347%	$123.4581	$123.46	$123.45	$123.50
Purchase #7	$235.49	6.328%	$250.3918	$250.39	$250.40	$250.40
7 purchase totals =	$963.19		$1,046.5726	$1,046.57	$1,046.65	$1,046.60