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	$212.34	6.279%	$225.6728	$225.67	$225.65	$225.70
Purchase #2	$188.40	7.250%	$202.059	$202.06	$202.05	$202.10
Purchase #3	$156.64	11.392%	$174.4844	$174.48	$174.50	$174.50
Purchase #4	$64.80	4.806%	$67.9143	$67.91	$67.90	$67.90
Purchase #5	$223.59	13.630%	$254.0653	$254.07	$254.05	$254.10
Purchase #6	$189.67	5.274%	$199.6732	$199.67	$199.65	$199.70
Purchase #7	$66.73	8.564%	$72.4448	$72.44	$72.45	$72.40
7 purchase totals =	$1,102.17		$1,196.3138	$1,196.30	$1,196.25	$1,196.40