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	$10.37	5.512%	$10.9416	$10.94	$10.95	$10.90
Purchase #2	$100.97	8.814%	$109.8695	$109.87	$109.85	$109.90
Purchase #3	$48.86	13.147%	$55.2836	$55.28	$55.30	$55.30
Purchase #4	$115.90	8.326%	$125.5498	$125.55	$125.55	$125.50
Purchase #5	$207.93	6.812%	$222.0942	$222.09	$222.10	$222.10
Purchase #6	$250.97	7.473%	$269.725	$269.73	$269.75	$269.70
Purchase #7	$220.30	4.195%	$229.5416	$229.54	$229.55	$229.50
7 purchase totals =	$955.30		$1,023.0053	$1,023.00	$1,023.05	$1,022.90