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	$146.89	3.494%	$152.0223	$152.02	$152.00	$152.00
Purchase #2	$54.54	3.145%	$56.2553	$56.26	$56.25	$56.30
Purchase #3	$208.56	10.730%	$230.9385	$230.94	$230.95	$230.90
Purchase #4	$213.49	11.873%	$238.8377	$238.84	$238.85	$238.80
Purchase #5	$37.26	5.689%	$39.3797	$39.38	$39.40	$39.40
Purchase #6	$64.35	5.500%	$67.8893	$67.89	$67.90	$67.90
Purchase #7	$221.41	3.621%	$229.4273	$229.43	$229.45	$229.40
7 purchase totals =	$946.50		$1,014.7501	$1,014.76	$1,014.80	$1,014.70