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	$155.37	5.650%	$164.1484	$164.15	$164.15	$164.10
Purchase #2	$128.51	4.817%	$134.7003	$134.70	$134.70	$134.70
Purchase #3	$107.33	11.404%	$119.5699	$119.57	$119.55	$119.60
Purchase #4	$6.27	5.314%	$6.6032	$6.60	$6.60	$6.60
Purchase #5	$166.27	9.740%	$182.4647	$182.46	$182.45	$182.50
Purchase #6	$229.43	4.753%	$240.3348	$240.33	$240.35	$240.30
Purchase #7	$162.61	7.204%	$174.3244	$174.32	$174.30	$174.30
7 purchase totals =	$955.79		$1,022.1457	$1,022.13	$1,022.10	$1,022.10