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	$92.70	4.503%	$96.8743	$96.87	$96.85	$96.90
Purchase #2	$234.86	4.480%	$245.3817	$245.38	$245.40	$245.40
Purchase #3	$27.29	9.133%	$29.7824	$29.78	$29.80	$29.80
Purchase #4	$124.39	4.715%	$130.255	$130.26	$130.25	$130.30
Purchase #5	$55.46	12.512%	$62.3992	$62.40	$62.40	$62.40
Purchase #6	$64.86	9.264%	$70.8686	$70.87	$70.85	$70.90
Purchase #7	$111.27	13.595%	$126.3972	$126.40	$126.40	$126.40
7 purchase totals =	$710.83		$761.9584	$761.96	$761.95	$762.10