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	$211.73	6.601%	$225.7063	$225.71	$225.70	$225.70
Purchase #2	$151.60	4.831%	$158.9238	$158.92	$158.90	$158.90
Purchase #3	$159.94	13.273%	$181.1688	$181.17	$181.15	$181.20
Purchase #4	$68.46	3.114%	$70.5918	$70.59	$70.60	$70.60
Purchase #5	$22.90	6.380%	$24.361	$24.36	$24.35	$24.40
Purchase #6	$196.38	13.469%	$222.8304	$222.83	$222.85	$222.80
Purchase #7	$125.26	12.686%	$141.1505	$141.15	$141.15	$141.20
7 purchase totals =	$936.27		$1,024.7326	$1,024.73	$1,024.70	$1,024.80