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	$171.45	6.572%	$182.7177	$182.72	$182.70	$182.70
Purchase #2	$13.48	10.460%	$14.89	$14.89	$14.90	$14.90
Purchase #3	$90.88	3.623%	$94.1726	$94.17	$94.15	$94.20
Purchase #4	$58.83	11.183%	$65.409	$65.41	$65.40	$65.40
Purchase #5	$187.74	4.408%	$196.0156	$196.02	$196.00	$196.00
Purchase #6	$191.32	5.534%	$201.9076	$201.91	$201.90	$201.90
Purchase #7	$9.74	4.353%	$10.164	$10.16	$10.15	$10.20
7 purchase totals =	$723.44		$765.2765	$765.28	$765.20	$765.30