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	$183.60	7.199%	$196.8174	$196.82	$196.80	$196.80
Purchase #2	$224.87	5.735%	$237.7663	$237.77	$237.75	$237.80
Purchase #3	$46.61	5.750%	$49.2901	$49.29	$49.30	$49.30
Purchase #4	$90.60	12.446%	$101.8761	$101.88	$101.90	$101.90
Purchase #5	$199.98	9.240%	$218.4582	$218.46	$218.45	$218.50
Purchase #6	$211.90	8.200%	$229.2758	$229.28	$229.30	$229.30
Purchase #7	$58.93	3.731%	$61.1287	$61.13	$61.15	$61.10
7 purchase totals =	$1,016.49		$1,094.6126	$1,094.63	$1,094.65	$1,094.70