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	$222.72	9.137%	$243.0699	$243.07	$243.05	$243.10
Purchase #2	$78.54	8.863%	$85.501	$85.50	$85.50	$85.50
Purchase #3	$241.91	3.474%	$250.314	$250.31	$250.30	$250.30
Purchase #4	$41.26	9.492%	$45.1764	$45.18	$45.20	$45.20
Purchase #5	$71.89	11.155%	$79.9093	$79.91	$79.90	$79.90
Purchase #6	$127.40	7.827%	$137.3716	$137.37	$137.35	$137.40
Purchase #7	$205.37	13.310%	$232.7047	$232.70	$232.70	$232.70
7 purchase totals =	$989.09		$1,074.0469	$1,074.04	$1,074.00	$1,074.10