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	$103.32	7.485%	$111.0535	$111.05	$111.05	$111.10
Purchase #2	$226.82	6.762%	$242.1576	$242.16	$242.15	$242.20
Purchase #3	$62.86	13.352%	$71.2531	$71.25	$71.25	$71.30
Purchase #4	$234.41	11.334%	$260.978	$260.98	$261.00	$261.00
Purchase #5	$184.63	7.455%	$198.3942	$198.39	$198.40	$198.40
Purchase #6	$100.26	9.621%	$109.906	$109.91	$109.90	$109.90
Purchase #7	$144.98	13.513%	$164.5711	$164.57	$164.55	$164.60
7 purchase totals =	$1,057.28		$1,158.3135	$1,158.31	$1,158.30	$1,158.50