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	$176.69	11.125%	$196.3468	$196.35	$196.35	$196.30
Purchase #2	$48.62	13.818%	$55.3383	$55.34	$55.35	$55.30
Purchase #3	$7.59	4.523%	$7.9333	$7.93	$7.95	$7.90
Purchase #4	$86.48	3.861%	$89.819	$89.82	$89.80	$89.80
Purchase #5	$240.51	11.563%	$268.3202	$268.32	$268.30	$268.30
Purchase #6	$143.78	9.430%	$157.3385	$157.34	$157.35	$157.30
Purchase #7	$198.90	13.476%	$225.7038	$225.70	$225.70	$225.70
7 purchase totals =	$902.57		$1,000.7999	$1,000.80	$1,000.80	$1,000.60