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	$97.61	11.743%	$109.0723	$109.07	$109.05	$109.10
Purchase #2	$192.90	3.132%	$198.9416	$198.94	$198.95	$198.90
Purchase #3	$181.69	9.187%	$198.3819	$198.38	$198.40	$198.40
Purchase #4	$209.27	8.472%	$226.9994	$227.00	$227.00	$227.00
Purchase #5	$174.56	7.161%	$187.0602	$187.06	$187.05	$187.10
Purchase #6	$146.57	3.114%	$151.1342	$151.13	$151.15	$151.10
Purchase #7	$35.45	11.553%	$39.5455	$39.55	$39.55	$39.50
7 purchase totals =	$1,038.05		$1,111.1351	$1,111.13	$1,111.15	$1,111.10