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	$141.32	3.105%	$145.708	$145.71	$145.70	$145.70
Purchase #2	$63.96	12.600%	$72.019	$72.02	$72.00	$72.00
Purchase #3	$146.39	13.474%	$166.1146	$166.11	$166.10	$166.10
Purchase #4	$213.68	9.113%	$233.1527	$233.15	$233.15	$233.20
Purchase #5	$208.35	10.233%	$229.6705	$229.67	$229.65	$229.70
Purchase #6	$12.75	12.292%	$14.3172	$14.32	$14.30	$14.30
Purchase #7	$152.97	6.443%	$162.8259	$162.83	$162.85	$162.80
7 purchase totals =	$939.42		$1,023.8079	$1,023.81	$1,023.75	$1,023.80