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	$92.51	11.580%	$103.2227	$103.22	$103.20	$103.20
Purchase #2	$146.85	11.868%	$164.2782	$164.28	$164.30	$164.30
Purchase #3	$200.81	5.320%	$211.4931	$211.49	$211.50	$211.50
Purchase #4	$26.60	6.443%	$28.3138	$28.31	$28.30	$28.30
Purchase #5	$222.38	5.519%	$234.6532	$234.65	$234.65	$234.70
Purchase #6	$236.96	11.686%	$264.6511	$264.65	$264.65	$264.70
Purchase #7	$194.85	9.228%	$212.8308	$212.83	$212.85	$212.80
7 purchase totals =	$1,120.96		$1,219.4429	$1,219.43	$1,219.45	$1,219.50