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	$114.94	10.700%	$127.2386	$127.24	$127.25	$127.20
Purchase #2	$86.83	11.116%	$96.482	$96.48	$96.50	$96.50
Purchase #3	$89.75	6.248%	$95.3576	$95.36	$95.35	$95.40
Purchase #4	$63.61	6.131%	$67.5099	$67.51	$67.50	$67.50
Purchase #5	$245.65	11.639%	$274.2412	$274.24	$274.25	$274.20
Purchase #6	$219.97	10.664%	$243.4276	$243.43	$243.45	$243.40
Purchase #7	$110.45	7.501%	$118.7349	$118.73	$118.75	$118.70
7 purchase totals =	$931.20		$1,022.9918	$1,022.99	$1,023.05	$1,022.90