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	$95.37	3.616%	$98.8186	$98.82	$98.80	$98.80
Purchase #2	$91.98	9.257%	$100.4946	$100.49	$100.50	$100.50
Purchase #3	$31.56	10.437%	$34.8539	$34.85	$34.85	$34.90
Purchase #4	$179.33	4.744%	$187.8374	$187.84	$187.85	$187.80
Purchase #5	$149.35	10.764%	$165.426	$165.43	$165.45	$165.40
Purchase #6	$190.56	3.503%	$197.2353	$197.24	$197.25	$197.20
Purchase #7	$196.41	10.265%	$216.5715	$216.57	$216.55	$216.60
7 purchase totals =	$934.56		$1,001.2373	$1,001.24	$1,001.25	$1,001.20