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	$203.26	11.349%	$226.328	$226.33	$226.35	$226.30
Purchase #2	$67.51	13.115%	$76.3639	$76.36	$76.35	$76.40
Purchase #3	$180.79	8.664%	$196.4536	$196.45	$196.45	$196.50
Purchase #4	$80.43	9.563%	$88.1215	$88.12	$88.10	$88.10
Purchase #5	$245.98	9.721%	$269.8917	$269.89	$269.90	$269.90
Purchase #6	$109.39	9.436%	$119.712	$119.71	$119.70	$119.70
Purchase #7	$33.65	12.663%	$37.9111	$37.91	$37.90	$37.90
7 purchase totals =	$921.01		$1,014.7818	$1,014.77	$1,014.75	$1,014.80