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	$213.71	4.150%	$222.579	$222.58	$222.60	$222.60
Purchase #2	$150.78	3.211%	$155.6215	$155.62	$155.60	$155.60
Purchase #3	$205.80	11.337%	$229.1315	$229.13	$229.15	$229.10
Purchase #4	$87.31	7.128%	$93.5335	$93.53	$93.55	$93.50
Purchase #5	$24.92	4.796%	$26.1152	$26.12	$26.10	$26.10
Purchase #6	$105.33	4.249%	$109.8055	$109.81	$109.80	$109.80
Purchase #7	$168.58	12.428%	$189.5311	$189.53	$189.55	$189.50
7 purchase totals =	$956.43		$1,026.3173	$1,026.32	$1,026.35	$1,026.20