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	$110.92	5.384%	$116.8919	$116.89	$116.90	$116.90
Purchase #2	$17.37	5.581%	$18.3394	$18.34	$18.35	$18.30
Purchase #3	$167.73	6.788%	$179.1155	$179.12	$179.10	$179.10
Purchase #4	$101.55	10.712%	$112.428	$112.43	$112.45	$112.40
Purchase #5	$213.86	5.564%	$225.7592	$225.76	$225.75	$225.80
Purchase #6	$171.79	9.594%	$188.2715	$188.27	$188.25	$188.30
Purchase #7	$176.47	8.445%	$191.3729	$191.37	$191.35	$191.40
7 purchase totals =	$959.69		$1,032.1784	$1,032.18	$1,032.15	$1,032.20