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	$208.56	4.675%	$218.3102	$218.31	$218.30	$218.30
Purchase #2	$203.56	8.763%	$221.398	$221.40	$221.40	$221.40
Purchase #3	$18.90	10.385%	$20.8628	$20.86	$20.85	$20.90
Purchase #4	$128.67	10.851%	$142.632	$142.63	$142.65	$142.60
Purchase #5	$86.80	12.148%	$97.3445	$97.34	$97.35	$97.30
Purchase #6	$207.27	10.347%	$228.7162	$228.72	$228.70	$228.70
Purchase #7	$112.67	9.629%	$123.519	$123.52	$123.50	$123.50
7 purchase totals =	$966.43		$1,052.7827	$1,052.78	$1,052.75	$1,052.70