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	$202.42	13.311%	$229.3641	$229.36	$229.35	$229.40
Purchase #2	$206.71	3.644%	$214.2425	$214.24	$214.25	$214.20
Purchase #3	$38.81	4.137%	$40.4156	$40.42	$40.40	$40.40
Purchase #4	$52.92	12.275%	$59.4159	$59.42	$59.40	$59.40
Purchase #5	$191.74	13.232%	$217.111	$217.11	$217.10	$217.10
Purchase #6	$145.61	11.318%	$162.0901	$162.09	$162.10	$162.10
Purchase #7	$137.71	10.129%	$151.6586	$151.66	$151.65	$151.70
7 purchase totals =	$975.92		$1,074.2978	$1,074.30	$1,074.25	$1,074.30