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	$184.78	12.584%	$208.0327	$208.03	$208.05	$208.00
Purchase #2	$229.69	6.134%	$243.7792	$243.78	$243.80	$243.80
Purchase #3	$161.51	5.150%	$169.8278	$169.83	$169.85	$169.80
Purchase #4	$26.36	8.196%	$28.5205	$28.52	$28.50	$28.50
Purchase #5	$89.96	12.277%	$101.0044	$101.00	$101.00	$101.00
Purchase #6	$222.80	12.419%	$250.4695	$250.47	$250.45	$250.50
Purchase #7	$136.73	10.208%	$150.6874	$150.69	$150.70	$150.70
7 purchase totals =	$1,051.83		$1,152.3215	$1,152.32	$1,152.35	$1,152.30