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	$156.94	6.489%	$167.1238	$167.12	$167.10	$167.10
Purchase #2	$75.78	3.138%	$78.158	$78.16	$78.15	$78.20
Purchase #3	$127.34	4.539%	$133.12	$133.12	$133.10	$133.10
Purchase #4	$105.92	13.236%	$119.9396	$119.94	$119.95	$119.90
Purchase #5	$145.53	8.829%	$158.3788	$158.38	$158.40	$158.40
Purchase #6	$151.35	12.243%	$169.8798	$169.88	$169.90	$169.90
Purchase #7	$185.74	5.216%	$195.4282	$195.43	$195.45	$195.40
7 purchase totals =	$948.60		$1,022.0282	$1,022.03	$1,022.05	$1,022.00