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	$116.29	9.501%	$127.3387	$127.34	$127.35	$127.30
Purchase #2	$139.55	12.216%	$156.5974	$156.60	$156.60	$156.60
Purchase #3	$86.48	11.506%	$96.4304	$96.43	$96.45	$96.40
Purchase #4	$171.88	13.519%	$195.1165	$195.12	$195.10	$195.10
Purchase #5	$61.97	5.309%	$65.26	$65.26	$65.25	$65.30
Purchase #6	$183.89	4.191%	$191.5968	$191.60	$191.60	$191.60
Purchase #7	$192.97	12.320%	$216.7439	$216.74	$216.75	$216.70
7 purchase totals =	$953.03		$1,049.0837	$1,049.09	$1,049.10	$1,049.00