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	$174.86	4.333%	$182.4367	$182.44	$182.45	$182.40
Purchase #2	$21.26	8.812%	$23.1334	$23.13	$23.15	$23.10
Purchase #3	$171.40	11.409%	$190.955	$190.96	$190.95	$191.00
Purchase #4	$188.70	4.319%	$196.85	$196.85	$196.85	$196.90
Purchase #5	$194.65	4.828%	$204.0477	$204.05	$204.05	$204.00
Purchase #6	$197.53	11.178%	$219.6099	$219.61	$219.60	$219.60
Purchase #7	$113.26	12.318%	$127.2114	$127.21	$127.20	$127.20
7 purchase totals =	$1,061.66		$1,144.2441	$1,144.25	$1,144.25	$1,144.20