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	$127.55	3.216%	$131.652	$131.65	$131.65	$131.70
Purchase #2	$173.44	8.822%	$188.7409	$188.74	$188.75	$188.70
Purchase #3	$117.66	8.270%	$127.3905	$127.39	$127.40	$127.40
Purchase #4	$207.78	13.184%	$235.1737	$235.17	$235.15	$235.20
Purchase #5	$157.73	4.212%	$164.3736	$164.37	$164.35	$164.40
Purchase #6	$143.36	4.802%	$150.2441	$150.24	$150.25	$150.20
Purchase #7	$197.72	13.639%	$224.687	$224.69	$224.70	$224.70
7 purchase totals =	$1,125.24		$1,222.2618	$1,222.25	$1,222.25	$1,222.30