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	$196.75	9.665%	$215.7659	$215.77	$215.75	$215.80
Purchase #2	$223.69	7.518%	$240.507	$240.51	$240.50	$240.50
Purchase #3	$94.32	10.259%	$103.9963	$104.00	$104.00	$104.00
Purchase #4	$62.27	9.311%	$68.068	$68.07	$68.05	$68.10
Purchase #5	$80.30	3.470%	$83.0864	$83.09	$83.10	$83.10
Purchase #6	$104.42	10.458%	$115.3402	$115.34	$115.35	$115.30
Purchase #7	$182.89	5.157%	$192.3216	$192.32	$192.30	$192.30
7 purchase totals =	$944.64		$1,019.0854	$1,019.10	$1,019.05	$1,019.10