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	$147.69	10.128%	$162.648	$162.65	$162.65	$162.60
Purchase #2	$64.34	12.308%	$72.259	$72.26	$72.25	$72.30
Purchase #3	$188.72	13.367%	$213.9462	$213.95	$213.95	$213.90
Purchase #4	$103.69	6.269%	$110.1903	$110.19	$110.20	$110.20
Purchase #5	$12.39	9.745%	$13.5974	$13.60	$13.60	$13.60
Purchase #6	$196.97	13.628%	$223.8131	$223.81	$223.80	$223.80
Purchase #7	$137.58	10.497%	$152.0218	$152.02	$152.00	$152.00
7 purchase totals =	$851.38		$948.4758	$948.48	$948.45	$948.40