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	$237.80	10.220%	$262.1032	$262.10	$262.10	$262.10
Purchase #2	$52.74	12.338%	$59.2471	$59.25	$59.25	$59.20
Purchase #3	$82.30	8.825%	$89.563	$89.56	$89.55	$89.60
Purchase #4	$122.95	13.305%	$139.3085	$139.31	$139.30	$139.30
Purchase #5	$175.26	4.365%	$182.9101	$182.91	$182.90	$182.90
Purchase #6	$191.33	11.568%	$213.4631	$213.46	$213.45	$213.50
Purchase #7	$206.87	4.504%	$216.1874	$216.19	$216.20	$216.20
7 purchase totals =	$1,069.25		$1,162.7824	$1,162.78	$1,162.75	$1,162.80