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	$162.98	13.111%	$184.3483	$184.35	$184.35	$184.30
Purchase #2	$200.96	11.413%	$223.8956	$223.90	$223.90	$223.90
Purchase #3	$199.27	12.220%	$223.6208	$223.62	$223.60	$223.60
Purchase #4	$142.38	7.507%	$153.0685	$153.07	$153.05	$153.10
Purchase #5	$91.30	3.857%	$94.8214	$94.82	$94.80	$94.80
Purchase #6	$20.38	8.564%	$22.1253	$22.13	$22.15	$22.10
Purchase #7	$180.49	8.801%	$196.3749	$196.37	$196.35	$196.40
7 purchase totals =	$997.76		$1,098.2548	$1,098.26	$1,098.20	$1,098.20