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	$196.32	3.229%	$202.6592	$202.66	$202.65	$202.70
Purchase #2	$247.37	11.311%	$275.35	$275.35	$275.35	$275.40
Purchase #3	$205.41	7.677%	$221.1793	$221.18	$221.20	$221.20
Purchase #4	$68.43	5.644%	$72.2922	$72.29	$72.30	$72.30
Purchase #5	$63.65	11.744%	$71.1251	$71.13	$71.15	$71.10
Purchase #6	$206.75	4.238%	$215.5121	$215.51	$215.50	$215.50
Purchase #7	$79.27	7.851%	$85.4935	$85.49	$85.50	$85.50
7 purchase totals =	$1,067.20		$1,143.6114	$1,143.61	$1,143.65	$1,143.70