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	$105.81	7.870%	$114.1372	$114.14	$114.15	$114.10
Purchase #2	$14.88	3.512%	$15.4026	$15.40	$15.40	$15.40
Purchase #3	$240.31	11.418%	$267.7486	$267.75	$267.75	$267.70
Purchase #4	$52.89	12.505%	$59.5039	$59.50	$59.50	$59.50
Purchase #5	$109.85	12.120%	$123.1638	$123.16	$123.15	$123.20
Purchase #6	$168.75	10.578%	$186.6004	$186.60	$186.60	$186.60
Purchase #7	$140.51	13.681%	$159.7332	$159.73	$159.75	$159.70
7 purchase totals =	$833.00		$926.2897	$926.28	$926.30	$926.20