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	$208.74	7.542%	$224.4832	$224.48	$224.50	$224.50
Purchase #2	$111.81	6.579%	$119.166	$119.17	$119.15	$119.20
Purchase #3	$191.30	13.797%	$217.6937	$217.69	$217.70	$217.70
Purchase #4	$159.66	9.541%	$174.8932	$174.89	$174.90	$174.90
Purchase #5	$54.40	13.160%	$61.559	$61.56	$61.55	$61.60
Purchase #6	$7.93	6.688%	$8.4604	$8.46	$8.45	$8.50
Purchase #7	$196.59	13.371%	$222.876	$222.88	$222.90	$222.90
7 purchase totals =	$930.43		$1,029.1315	$1,029.13	$1,029.15	$1,029.30