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	$70.68	6.702%	$75.417	$75.42	$75.40	$75.40
Purchase #2	$147.51	11.520%	$164.5032	$164.50	$164.50	$164.50
Purchase #3	$168.83	10.868%	$187.1784	$187.18	$187.20	$187.20
Purchase #4	$222.55	13.792%	$253.2441	$253.24	$253.25	$253.20
Purchase #5	$188.51	3.599%	$195.2945	$195.29	$195.30	$195.30
Purchase #6	$32.80	13.277%	$37.1549	$37.15	$37.15	$37.20
Purchase #7	$107.89	4.296%	$112.525	$112.53	$112.55	$112.50
7 purchase totals =	$938.77		$1,025.3171	$1,025.31	$1,025.35	$1,025.30