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	$213.42	13.463%	$242.1527	$242.15	$242.15	$242.20
Purchase #2	$72.27	13.525%	$82.0445	$82.04	$82.05	$82.00
Purchase #3	$197.63	7.532%	$212.5155	$212.52	$212.50	$212.50
Purchase #4	$216.38	10.169%	$238.3837	$238.38	$238.40	$238.40
Purchase #5	$187.88	3.801%	$195.0213	$195.02	$195.00	$195.00
Purchase #6	$45.40	11.391%	$50.5715	$50.57	$50.55	$50.60
Purchase #7	$20.84	11.674%	$23.2729	$23.27	$23.25	$23.30
7 purchase totals =	$953.82		$1,043.9621	$1,043.95	$1,043.90	$1,044.00