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	$213.39	5.146%	$224.371	$224.37	$224.35	$224.40
Purchase #2	$59.34	8.389%	$64.318	$64.32	$64.30	$64.30
Purchase #3	$138.91	8.172%	$150.2617	$150.26	$150.25	$150.30
Purchase #4	$42.44	6.359%	$45.1388	$45.14	$45.15	$45.10
Purchase #5	$143.38	4.711%	$150.1346	$150.13	$150.15	$150.10
Purchase #6	$145.49	7.654%	$156.6258	$156.63	$156.65	$156.60
Purchase #7	$76.39	6.555%	$81.3974	$81.40	$81.40	$81.40
7 purchase totals =	$819.34		$872.2473	$872.25	$872.25	$872.20