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	$234.25	4.807%	$245.5104	$245.51	$245.50	$245.50
Purchase #2	$217.48	13.777%	$247.4422	$247.44	$247.45	$247.40
Purchase #3	$69.55	4.817%	$72.9002	$72.90	$72.90	$72.90
Purchase #4	$105.72	3.511%	$109.4318	$109.43	$109.45	$109.40
Purchase #5	$146.33	3.130%	$150.9101	$150.91	$150.90	$150.90
Purchase #6	$111.71	5.312%	$117.644	$117.64	$117.65	$117.60
Purchase #7	$191.65	12.258%	$215.1425	$215.14	$215.15	$215.10
7 purchase totals =	$1,076.69		$1,158.9812	$1,158.97	$1,159.00	$1,158.80