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	$221.56	7.848%	$238.948	$238.95	$238.95	$238.90
Purchase #2	$103.35	6.776%	$110.353	$110.35	$110.35	$110.40
Purchase #3	$60.74	3.493%	$62.8616	$62.86	$62.85	$62.90
Purchase #4	$143.38	10.738%	$158.7761	$158.78	$158.80	$158.80
Purchase #5	$79.59	4.713%	$83.3411	$83.34	$83.35	$83.30
Purchase #6	$168.64	6.384%	$179.406	$179.41	$179.40	$179.40
Purchase #7	$243.95	6.416%	$259.6018	$259.60	$259.60	$259.60
7 purchase totals =	$1,021.21		$1,093.2876	$1,093.29	$1,093.30	$1,093.30