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	$100.46	10.856%	$111.3659	$111.37	$111.35	$111.40
Purchase #2	$148.67	12.505%	$167.2612	$167.26	$167.25	$167.30
Purchase #3	$146.31	6.707%	$156.123	$156.12	$156.10	$156.10
Purchase #4	$93.25	13.757%	$106.0784	$106.08	$106.10	$106.10
Purchase #5	$90.84	7.514%	$97.6657	$97.67	$97.65	$97.70
Purchase #6	$247.95	13.514%	$281.458	$281.46	$281.45	$281.50
Purchase #7	$148.41	10.655%	$164.2231	$164.22	$164.20	$164.20
7 purchase totals =	$975.89		$1,084.1753	$1,084.18	$1,084.10	$1,084.30