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	$13.25	12.790%	$14.9447	$14.94	$14.95	$14.90
Purchase #2	$223.79	4.255%	$233.3123	$233.31	$233.30	$233.30
Purchase #3	$93.29	9.568%	$102.216	$102.22	$102.20	$102.20
Purchase #4	$153.37	11.673%	$171.2729	$171.27	$171.25	$171.30
Purchase #5	$41.27	3.674%	$42.7863	$42.79	$42.80	$42.80
Purchase #6	$130.80	12.578%	$147.252	$147.25	$147.25	$147.30
Purchase #7	$51.37	11.574%	$57.3156	$57.32	$57.30	$57.30
7 purchase totals =	$707.14		$769.0998	$769.10	$769.05	$769.10