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	$246.53	9.219%	$269.2576	$269.26	$269.25	$269.30
Purchase #2	$13.25	4.817%	$13.8883	$13.89	$13.90	$13.90
Purchase #3	$235.37	3.610%	$243.8669	$243.87	$243.85	$243.90
Purchase #4	$158.80	7.112%	$170.0939	$170.09	$170.10	$170.10
Purchase #5	$56.66	10.641%	$62.6892	$62.69	$62.70	$62.70
Purchase #6	$144.95	12.220%	$162.6629	$162.66	$162.65	$162.70
Purchase #7	$91.85	9.196%	$100.2965	$100.30	$100.30	$100.30
7 purchase totals =	$947.41		$1,022.7553	$1,022.76	$1,022.75	$1,022.90