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	$42.47	5.156%	$44.6598	$44.66	$44.65	$44.70
Purchase #2	$97.29	6.441%	$103.5564	$103.56	$103.55	$103.60
Purchase #3	$109.76	9.252%	$119.915	$119.92	$119.90	$119.90
Purchase #4	$235.83	13.482%	$267.6246	$267.62	$267.60	$267.60
Purchase #5	$59.48	3.581%	$61.61	$61.61	$61.60	$61.60
Purchase #6	$242.92	6.454%	$258.5981	$258.60	$258.60	$258.60
Purchase #7	$147.37	7.393%	$158.2651	$158.27	$158.25	$158.30
7 purchase totals =	$935.12		$1,014.2290	$1,014.24	$1,014.15	$1,014.30