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	$159.49	13.799%	$181.498	$181.50	$181.50	$181.50
Purchase #2	$95.37	3.736%	$98.933	$98.93	$98.95	$98.90
Purchase #3	$171.52	12.780%	$193.4403	$193.44	$193.45	$193.40
Purchase #4	$179.56	6.310%	$190.8902	$190.89	$190.90	$190.90
Purchase #5	$192.89	10.764%	$213.6527	$213.65	$213.65	$213.70
Purchase #6	$54.25	11.519%	$60.4991	$60.50	$60.50	$60.50
Purchase #7	$81.97	5.694%	$86.6374	$86.64	$86.65	$86.60
7 purchase totals =	$935.05		$1,025.5507	$1,025.55	$1,025.60	$1,025.50