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	$123.37	8.575%	$133.949	$133.95	$133.95	$133.90
Purchase #2	$37.90	9.653%	$41.5585	$41.56	$41.55	$41.60
Purchase #3	$82.97	8.210%	$89.7818	$89.78	$89.80	$89.80
Purchase #4	$20.26	9.169%	$22.1176	$22.12	$22.10	$22.10
Purchase #5	$152.66	4.400%	$159.377	$159.38	$159.40	$159.40
Purchase #6	$107.30	11.709%	$119.8638	$119.86	$119.85	$119.90
Purchase #7	$169.88	6.478%	$180.8848	$180.88	$180.90	$180.90
7 purchase totals =	$694.34		$747.5325	$747.53	$747.55	$747.60