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	$88.93	7.342%	$95.4592	$95.46	$95.45	$95.50
Purchase #2	$40.54	7.243%	$43.4763	$43.48	$43.50	$43.50
Purchase #3	$250.45	9.853%	$275.1268	$275.13	$275.15	$275.10
Purchase #4	$34.34	8.872%	$37.3866	$37.39	$37.40	$37.40
Purchase #5	$58.66	3.635%	$60.7923	$60.79	$60.80	$60.80
Purchase #6	$245.41	11.436%	$273.4751	$273.48	$273.50	$273.50
Purchase #7	$208.83	6.506%	$222.4165	$222.42	$222.40	$222.40
7 purchase totals =	$927.16		$1,008.1328	$1,008.15	$1,008.20	$1,008.20