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	$154.38	8.712%	$167.8296	$167.83	$167.85	$167.80
Purchase #2	$44.62	4.708%	$46.7207	$46.72	$46.70	$46.70
Purchase #3	$47.44	5.752%	$50.1687	$50.17	$50.15	$50.20
Purchase #4	$79.68	7.747%	$85.8528	$85.85	$85.85	$85.90
Purchase #5	$222.45	3.350%	$229.9021	$229.90	$229.90	$229.90
Purchase #6	$162.27	11.109%	$180.2966	$180.30	$180.30	$180.30
Purchase #7	$192.72	9.709%	$211.4312	$211.43	$211.45	$211.40
7 purchase totals =	$903.56		$972.2017	$972.20	$972.20	$972.20