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	$95.41	7.799%	$102.851	$102.85	$102.85	$102.90
Purchase #2	$160.56	11.809%	$179.5205	$179.52	$179.50	$179.50
Purchase #3	$140.78	11.683%	$157.2273	$157.23	$157.25	$157.20
Purchase #4	$248.50	3.382%	$256.9043	$256.90	$256.90	$256.90
Purchase #5	$200.62	5.363%	$211.3793	$211.38	$211.40	$211.40
Purchase #6	$165.46	3.443%	$171.1568	$171.16	$171.15	$171.20
Purchase #7	$105.42	13.581%	$119.7371	$119.74	$119.75	$119.70
7 purchase totals =	$1,116.75		$1,198.7763	$1,198.78	$1,198.80	$1,198.80