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	$230.94	5.381%	$243.3669	$243.37	$243.35	$243.40
Purchase #2	$48.89	6.232%	$51.9368	$51.94	$51.95	$51.90
Purchase #3	$125.78	4.787%	$131.8011	$131.80	$131.80	$131.80
Purchase #4	$239.25	10.571%	$264.5411	$264.54	$264.55	$264.50
Purchase #5	$56.46	13.856%	$64.2831	$64.28	$64.30	$64.30
Purchase #6	$250.57	13.554%	$284.5323	$284.53	$284.55	$284.50
Purchase #7	$47.32	13.554%	$53.7338	$53.73	$53.75	$53.70
7 purchase totals =	$999.21		$1,094.1951	$1,094.19	$1,094.25	$1,094.10