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	$194.50	7.636%	$209.352	$209.35	$209.35	$209.40
Purchase #2	$56.79	3.258%	$58.6402	$58.64	$58.65	$58.60
Purchase #3	$250.80	12.307%	$281.666	$281.67	$281.65	$281.70
Purchase #4	$78.75	13.426%	$89.323	$89.32	$89.30	$89.30
Purchase #5	$34.66	4.487%	$36.2152	$36.22	$36.20	$36.20
Purchase #6	$41.75	3.306%	$43.1303	$43.13	$43.15	$43.10
Purchase #7	$35.26	5.152%	$37.0766	$37.08	$37.10	$37.10
7 purchase totals =	$692.51		$755.4033	$755.41	$755.40	$755.40