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	$226.82	7.442%	$243.6999	$243.70	$243.70	$243.70
Purchase #2	$93.54	7.650%	$100.6958	$100.70	$100.70	$100.70
Purchase #3	$97.64	3.190%	$100.7547	$100.75	$100.75	$100.80
Purchase #4	$222.99	9.197%	$243.4984	$243.50	$243.50	$243.50
Purchase #5	$92.77	12.683%	$104.536	$104.54	$104.55	$104.50
Purchase #6	$101.74	13.430%	$115.4037	$115.40	$115.40	$115.40
Purchase #7	$171.59	10.681%	$189.9175	$189.92	$189.90	$189.90
7 purchase totals =	$1,007.09		$1,098.5060	$1,098.51	$1,098.50	$1,098.50