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	$204.73	3.384%	$211.6581	$211.66	$211.65	$211.70
Purchase #2	$148.52	11.415%	$165.4736	$165.47	$165.45	$165.50
Purchase #3	$131.68	5.602%	$139.0567	$139.06	$139.05	$139.10
Purchase #4	$104.59	3.142%	$107.8762	$107.88	$107.90	$107.90
Purchase #5	$139.29	9.679%	$152.7719	$152.77	$152.75	$152.80
Purchase #6	$57.50	11.683%	$64.2177	$64.22	$64.20	$64.20
Purchase #7	$164.40	12.132%	$184.345	$184.35	$184.35	$184.30
7 purchase totals =	$950.71		$1,025.3992	$1,025.41	$1,025.35	$1,025.50