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	$197.30	13.310%	$223.5606	$223.56	$223.55	$223.60
Purchase #2	$78.80	13.278%	$89.2631	$89.26	$89.25	$89.30
Purchase #3	$208.81	3.701%	$216.5381	$216.54	$216.55	$216.50
Purchase #4	$181.69	7.141%	$194.6645	$194.66	$194.65	$194.70
Purchase #5	$138.49	10.571%	$153.1298	$153.13	$153.15	$153.10
Purchase #6	$132.48	3.782%	$137.4904	$137.49	$137.50	$137.50
Purchase #7	$175.79	11.777%	$196.4928	$196.49	$196.50	$196.50
7 purchase totals =	$1,113.36		$1,211.1393	$1,211.13	$1,211.15	$1,211.20