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	$195.82	4.834%	$205.2859	$205.29	$205.30	$205.30
Purchase #2	$217.67	4.344%	$227.1256	$227.13	$227.15	$227.10
Purchase #3	$182.74	7.689%	$196.7909	$196.79	$196.80	$196.80
Purchase #4	$92.36	5.792%	$97.7095	$97.71	$97.70	$97.70
Purchase #5	$86.31	5.561%	$91.1097	$91.11	$91.10	$91.10
Purchase #6	$89.65	11.373%	$99.8459	$99.85	$99.85	$99.80
Purchase #7	$173.48	6.472%	$184.7076	$184.71	$184.70	$184.70
7 purchase totals =	$1,038.03		$1,102.5751	$1,102.59	$1,102.60	$1,102.50