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	$98.63	4.525%	$103.093	$103.09	$103.10	$103.10
Purchase #2	$75.90	12.533%	$85.4125	$85.41	$85.40	$85.40
Purchase #3	$59.66	8.635%	$64.8116	$64.81	$64.80	$64.80
Purchase #4	$118.69	13.143%	$134.2894	$134.29	$134.30	$134.30
Purchase #5	$227.64	4.773%	$238.5053	$238.51	$238.50	$238.50
Purchase #6	$171.74	4.656%	$179.7362	$179.74	$179.75	$179.70
Purchase #7	$208.94	4.537%	$218.4196	$218.42	$218.40	$218.40
7 purchase totals =	$961.20		$1,024.2676	$1,024.27	$1,024.25	$1,024.20