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	$88.52	7.695%	$95.3316	$95.33	$95.35	$95.30
Purchase #2	$153.28	7.703%	$165.0872	$165.09	$165.10	$165.10
Purchase #3	$14.89	6.839%	$15.9083	$15.91	$15.90	$15.90
Purchase #4	$46.72	9.384%	$51.1042	$51.10	$51.10	$51.10
Purchase #5	$229.92	6.272%	$244.3406	$244.34	$244.35	$244.30
Purchase #6	$67.54	5.404%	$71.1899	$71.19	$71.20	$71.20
Purchase #7	$166.43	12.856%	$187.8262	$187.83	$187.85	$187.80
7 purchase totals =	$767.30		$830.7880	$830.79	$830.85	$830.70